PROSPECTING, LOCATING AND VALUING A Practical Treatise for the use of Prospectors, Investors and Mining Men. generally; with an account of the Principal Minerals and Country Rocks; Ore Deposits; Locations and Patents; the Early Development of Mines; Earthy Mineral Products; Coal; Gold Gravels and Gravel Mining; Measurement of Water; and Artesian Wells. WITH FIFTEEN PLATES. BY R* R STRETCH, E.M* SECOND EDITION. THE SCIENTIFIC PUBLISHING COMPANY: NEW YORK AND LONDON. 1900. 206 BOSTON BUILDING^ DENVER, COLO. COPYRIGHT, 1899, BY THE SCIENTIFIC PUBLISHING COMPANY CONTENTS. I. Introductory Mistakes in Mining. ....... 1 II. What Constitutes a Mine . . . r , 16 III. Rock-forming Minerals and Rocks 3 . . . . t 36 IV. Physical Character of Mineral Deposits 69 V. Origin of Veins , . 83 VI. Filling of Mineral Veins 4 . . , 99 VII. Influence of Rocks on Vein Filling , . , 120 VIII. Mineral Deposits Other than Veins . . , 138 IX. Prospecting . . . . a . 150 X. Making Locations ;>." 167 XI. Patents to Mining Ground 187 XII. Early Development of Mines. . * 197 XIII. Ores .. ... 206 XIV, Useful Earthy Minerals, etc 229 XV. Coal ,.,o 259 XVI. Gold Gravel Deposits 271 XVII. Water and Its Measurement 302 XVIII. Artesian Wells 310 Useful Tables 316 Good Books of Reference.. 338 Plates 1 to 15 inclusive. , 344 Index... . 374 438579 PROSPECTING, LOCATING ..AND.. VALUING MINES. CHAPTEK I. INTRODUCTORY MISTAKES IN MINING. THE following pages are not intended for those who have devoted a lifetime to mining and are educated in the many branches of knowledge which go to make the successful mining man, but for those who would like to invest a portion of their capital in the business if they felt safe in so doing, and who hold back because of their complete ignorance of the subject ; and to restrain the over-sanguine temperaments of others, by pointing out the elements which may militate against success. At the same time it is believed that the prospector will also find hints which will assist him in his \\ ^arisome labors, enable him to ma*ke his locations to better ad- vantage than is now the case in a very large proportion of those on record, and furnish him with the language in which he can intelligently describe to others what he has found, so that they shall see it just as he does, and be able to verify his statements upon inspection. It is hoped that the explanations and suggestions will, to some extent at least, prevent him from spend- ing time and money on valueless prospects or worthless minerals; furnish him with the means to determine approximately the value of what he has found, and 2 PROSPECTING AND VALUING MINES. show him the way to develop it at the least expendi- ture of time and labor; and enable him to see clearly what nature has done to his advantage, or the obstacles which have been thrown in his way. It is not pretended that new geological facts have been presented. Nearly all of them can be found in the books, but they are scattered through many and often expensive works, and in but few cases is there any allusion to the practical bearing of these facts on the interests of the miner, except in the case of coal mining, which has a complete and extensive literature of its own. In all these works, geology, in its relation to coal mining, receives full attention, but it has been otherwise with vein mining for the precious metals. Where it would be impossible to put the subject matter into better language, the writer has quoted freely from recognized authorities, and has used some illustrations which may almost be called common property from the frequency with which they have been copied by one writer after another; but a large proportion of the illustrations are drawn from the writer's own note- books. The object of the book may be best illustrated by a few words on the causes of failure of mining enter- prises which it is sought to avoid by calling special attention thereto. In mercantile business, failures arise from undue competition, depression in trade, wrong selection of location,* want of capital, lack of business tact, want of knowledge of the trade, etc. In gold mining, and to a certain extent in silver mining, we get rid of the element of competition ; and in gold mining, at least, depression in trade does not affect otherwise than as a stimulus, but ail other causes operate in very much the same manner both in mining and trade. It should be kept in mind that every pound of ore taken from a mine leaves just that much less in it, and that the end must inevitably come at some time. In INTRODUCTORY. 3 this respect a mine differs essentially from a mercan- tile business which can enlarge its field of operations year after year as population increases or facilities of communication are improved. If the mine only yields, above working expenses, a sum sufficient to repay the cost of the ground, development and plant, the investor might just as well have buried his dollars for the same period of time, and saved labor and mental strain. This state of affairs may easily occur even when the mine has rich ore in sight. It takes just as deep a shaft to open a piece of ground 500 ft. long as if it were 2,000, but the cost of sinking and pumping, and all expenses of corporate management will be four times as great per square foot of area developed in one case as in the other, and this difference may do away with the possibility of dividends or even the recovery of the invested capital. Numerous cases of this kind have been seen in Colo- rado and elsewhere, where small properties which could not stand the burdens thus imposed upon them have proved successful when consolidated, one shaft answering for a much larger property, thus saving the cost of constant sinking, the expense of numerous engines and surface hands, as well as superintendence and office expenses. On the other hand an enterprise may have so much ground that the energies of the company are scattered over too large an area, one unproductive section eat- ing up the profits of the better ground, thus leading to constant embarrassment; and a failure under these circumstances may do as much to blast the reputation of a district as if the property had been absolutely barren throughout. This condition of the mine as regards its capital renders it undesirable, if not dangerous, to experiment with new processes of reduction. So many of these, while eminently successful in the laboratory, when worked on a small scale and by enthusiasts thoroughly 4 PROSPECTING AND VALUING MINES. posted on all the minute details, have proved so inap- plicable on a large scale, when operated by less careful men, that a mine cannot afford to employ them until they have proved entirely satisfactory under all similar working conditions. The cost of the experiments should be borne by the projectors of the innovations; all that a mine dare do is to pay a royalty or purchase the machinery when it is no longer an experiment. It is true that the improved machinery, so called, might be a real improvement and a desirable acquisi- tion, but on the other hand, if a failure, it would be only another tax on a treasury which has already its full share of burdens. Again, the price given for a mine may be so exorbi- tant, or out of proportion to its development, that while it may pay dividends for a time and apparently be a success, the ore body may "peter out" before the purchase price has been returned in the shape of divi- dends; and failure will ensue, unless a reserve fund has been set aside, with which to search for other ore bodies, The disproportionate profits of the middlemen or promoters emphasize this proposition, as in the case of the Kichmond Consolidated mine in Nevada> which is said to have cost the stockholders $1,375,000 while the vendors received about $280,000, leaving the promoters a clean profit of over a million dollars. Luckily the mine repaid this enormous purchase price, but had it nut, it would have been condemned as a failure, when it was not legitimately entitled to be saddled with so great a burden. This was strictly gambling, not mining. The same thing has happened in floating the mines of many other districts, and notably so in the case of the Transvaal usually with a less fortunate outcome. A common cause of failure is in not keeping the development of the mine ahead of its current necessities. Such work will naturally reduce the dividends for a time, but it is far preferable to pay INTRODUCTORY. 5 for these developments out of the profits of the mine, while it is prosperous, than to have to raise an asess- ment for the purpose when it is looking poor. Those who have tried the latter plan know the attendant difficulties, which are especially conspicuous in the case of mines represented by unassessable stock. To such mines an empty treasury means almost inevi- table death, although a little medicine in the shape of coin might give them a long lease of life. It always happens that there are some stockholders who will not advance any more capital, and the rest do not feel inclined to do so and allow the non-payees to come in and reap the benefits; while there is no way in which undesirable partners like the non-paying stock- holders can be got rid of, except by foreclosure of a judgment for an indebtedness of the property. Another frequent source of lost money is the erec- tion of mills or other reduction works before they are required. Nevada is full of illustrations of this kind of folly, which is more apt to be committed by com- panies than by individuals. In many cases magnifi- cent mills were erected before the mine had been opened even sufficiently to know if there was a mine at all, and never dropped a stamp. Some of these enter- prises were unmitigated swindles and seriously hurt our mining interests abroad, so that the recovery of confidence took years to complete. Not a few of these mills were also utterly unsuited to the ore of the dis- trict and were consequently valueless even for custom use on the ore of other mines. In other cases the mills have been too large for the property for which they were erected, and it has been impossible to keep them running steadily to their injury, as machinery deteriorates rapidly from idleness. It would seem that few miners have any idea of the amount of ore which even a 10-stamp mill will consume in a year. We often hear that a mine is ready for a mill, when it has only a shaft from 50 to 100 ft. deep, or a tunnel of 6 PROSPECTING AND VALUING MINES. the same length. The absurdity of this proposition is apparent. There may of course be instances where the outcrop is so continuously in ore that there can be no doubt of our ability to put the mine in shape for extraction during the time consumed in the erection of a mill, but this is quite exceptional. Serious troubles have also arisen from false expecta- tions based on small quantities of rich ore, or rather of narrow seams. If these could be taken out by them- selves they would often pay handsomely, even when the quantities would not warrant the erection of a mill, but as they cannot be extracted without removing a large quantity of waste, the cost of doing this has to be taken into consideration, as well as the difficulty of preventing the loss of ore by mixture with the waste, even when carefully hand-sorted. It is not intended to intimate that these very small veins or seams may not be worth working, for seams of very diminutive thickness are worked at the mines at Nagyag in Tran- sylvania; and in some cases, as the native silver mines of Batopilas in Mexico, the sheet of ore is so tough that when less than an inch in thickness it may be left standing while the drift is run alongside, and stripped down once a week or oftener, as may be desirable. The object is to call attention to the frequent excessive cost of working very narrow ore seams, that due allowance may be made and failure avoided. Want of knowledge of the structure of the deposit is often a source of costly errors. It is not many years ago that the writer saw a summer's work thrown away by a superintendent losing the vein and not knowing how to find it again. Starting on the vein he apparently mistook the bedding of the rock for the wall, as shown in pi. 6., fig. 2, and on reaching the point B, where the ore apparently pinched out, went off into the country rock along a small seam in the hanging wall S. Not finding the large ore body which was known by its outcrop to exist ahead of the tunnel, INTRODUCTORY. 7 he crosscut in the wrong direction at A toward (7, when finding another small seam he turned back on that toward the main vein again. Had he continued on the line A C he would have come out to daylight in a direction exactly opposite to that in which he should have sought the ore body. The tunnel was run in hard granite under very adverse circumstances, entailing a serious outlay of money, which must be charged against any future profits, because whatever is spent on a mine ought to come out of it, and at the end of the season's work the property w ? as in a less satisfactory condition than before the tunnel was run ; as many observers would naturally come to the con- clusion that the mine was practically worthless, if the ore seen on the surface was lost so promptly in depth. (It has since been satisfactorily opened in the right direction.) The same amount of money properly ex- pended under judicious management would have taken the tunnel through a body of ore which crops continu- ously for several hundred feet, and would have been extracting ore for its entire length, thus making a profit instead of a loss, and putting the mine in shape for stoping. A most astonishing want of common sense in read- ing the lesson of the outcrop has caused the loss of much time and money. In the case of the mine shown in pi. 12, fig. 5, the outcrop of the vein occupied the fiat slope of a valley with a steep hill to the north, and was scattered over a width of 100 ft. for a consid- erable distance, but was not continuous, being broken up into little patches of varying size. The ore was rich, and being stained with the blue and green car- bonates of copper, was very conspicuous by contrast with the underlying yellowish limestones. Evidently this was mistaken for the outcrop of an immense vein or bed, but a very casual examination showed that the vein was only a thin film between the slates S and limestones L, for the little gulches running north to 8 PROSPECTING AND VALUING MINES. the main ravine had cut through the ore in numerous places, in all cases revealing the underlying limestone, and showing the true character of the deposit. That it was not understood was proved by the company running the tunnel Tto cut the vein. This was started in the foot wall and beneath the seam, and naturally never encountered ore. Had any further proof been wanting, nature had furnished it, for at the eastern end of the location, the bluffs (overlooking Death Valley, Cal.) broke down perpendicularly for several hundred feet, and had the vein been other than it was it must have shown conspicuously on the face of these precipices, which it did not. It would seem that this idea had never occurred to the purchasers, who were out of pocket on the transaction from $100,000 to $150,000 in purchase money and working expenses, while another mining failure was talked about and nothing said of the folly of the investors and man- agers, who would not believe the facts of the case even when they had paid to find them out. Again, it is only recently that a man professing to be a mining engineer recommended the exploitation of a bed of bog iron ore, when a casual investigation showed that it was a deposit now forming, only a few inches thick, limited to a few acres of marshy ground, and did not show a few hundred feet to the westward, where the ground breaks down abruptly in a bluff to the seashore, consisting entirely of unconsolidated sand and gravel. Investors in such a scheme would have faced certain failure from the start, and would unanimously have condemned mining as a business. Another method of losing money is to sink or bore for metals, coal or oil, or any other substance occur- ring in beds or bedded veins, when nature has told the whole story on the upturned edges of the rocks, as shown in pi. 4, fig. 4, and pi. 3, fig. 5. In pi. 4, fig. 4, a shaft sunk at D would disclose no more informa- tion than could be gained by walking over the country INTRODUCTORY 9 toward B, when tbe observer will pass over all the rock strata which would be cut in the shaft, with an immensely better opportunity of examining them in detail and without cost. If there is anything of value shown, as a coal seam at B, its merits can be discussed before the expenditure of a dollar for underground workings, and an incline could be sunk on it to greater advantage than the vertical shaft Z>, at least until a full knowledge of its character had been obtained. This mistake has been repeated so often that every person connected with mining must be able to recall instances. The same might be said of a shaft at B, pi. 3, fig. 5, but at A } in the same figure, a shaft would be excusable. In the neighborhood of Leadville, Colo., the writer has seen a prospector sinking in the granite to find carbonate of lead ore, which was an absolutely hopeless undertaking, as can be seen by reference to the cross section of the Leadville district, pi. 1, fig. 2, where the granite and gneiss underlie everything arid the ore is associated with the porphyry and limestone beds above it. The utter improbability of success would have been apparent to the prospector had he possessed even a smattering of knowledge of rocks and the occurrence of ore, but his shaft was another mem- ber of the army of failures for want of that knowledge. To him the proposition was plain that because others had sunk shafts and found ore at varying depths, without any surface showing, he had just as good a chance as they. On the other hand the want of the necessary preliminary exploration by boring, in the case of coal fields especially (after the presence of coal is known), may entail loss and failure owing to the breaking up of the beds by faults, the presence of which would have been made evident by a proper series of borings in each direction. The beds might not be ' 'faulted" or broken so regularly as in the idealized cross section on pi. 1, fig. 1, which shows a series of "step faults," but the figure will illustrate 10 PROSPECTING AND VALUING MINKS. the general idea. Let B, E, F and H represent bor- ings. If only B and jEf have been made, the coal seam, represented by the heavy black line, would have been found in each, and its dip fairly ascertained, but no indication of the faults A and B would have been de- tected, unless the bore hole //had been carried down some distance below the coal, and the works for the extraction of coal, based on these borings alone, might be valueless for working the bed between the faults B and G. But if the borings had been extended over a larger area and included others at E and F 9 the broken nature of the formation would have been disclosed and led to a thorough investigation as to whether the locality could be profitably worked, and if not the cost of permanent works would have been avoided. What has been said of coal applies to many of the gold gravel mines in California as well. Even if the quantity and quality of the material, such as coal, iron ore, clay and other minerals, which come into severe competition with each other, and require every facility in the way of cheap labor, cheap transportation, and an extended market for successful production, be all that can be asked, the deposits may be so situated with regard to the latter requirements that commercial failure must result from their explora- tion. Andre, in his treatise on coal mining, p. 80, puts the case very clearly : "But if certain clearly apparent circumstances exist which are sufficient of themselves to show that the undertaking cannot be commercially successful, even if all the other circumstances should prove favorable, it is plain to ordinary common sense that it would be sheer folly to prosecute a search which must necessarily be an expensive one, and which must as necessarily end in disappointment. Enormous sums of money have been expended in this way to the great and mani- fest injury of all legitimate enterprise." Every mining man can undoubtedly recall numerous INTRODUCTORY. H cases where labor has been expended on worthless minerals which a very slight knowledge of mineralogy would have saved. The writer has seen a shaft sunk on a body of black obsidian (volcanic glass), under the belief that it was anthracite coal. In another case the men were prospecting for coal in a narrow canon between basaltic walls, on the strength of a few pieces of carbonized wood in the gravel beds filling the gorge. In another instance several shafts were sunk on a deposit of red jaspery clay, carrying specks of iron pyrite, the prospector mistaking it for cinnabar on account of its bright red color, having probably heard that cinnabar was red, without knowing that usually it assumed that brilliant tint only when scratched or pulverized. For years a prospector in Washington spent money on and clung to the idea that he could develop an iron mine out of a body of clay slate, mixed with quartz and large quantities of iron pyrite, not knowing that the sulphur of the pyrite was a most undesirable constituent in iron, and that there was no probability of the deposit changing its character. Then again tin is an ever- recurring ignis fatuus. Recently the writer was assured in perfect good faith by a person willing to prove his faith by his works (if he could get some one to join him), that he had pounded pure tin out of the ore in a common mortar; and another could not be convinced that the polishing of the mortar while grinding so-called tin ore was not a coating of that metal, the iron as he called it being "galvanized!" Such stories lie at the bottom of many a newspaper item, and hundreds of such wild-goose propositions come before the mining engineer and mining men generally every year. But many a prospector will spend the best years of his life on such schemes, and not infrequently drag his equally uninformed friends into them, for want of a little knowledge so easily obtained. 12 PROSPECTING AND VALUING MINES. Yet another common source of loss is the failure to ascertain the true value of the ore and the probable character and quantity before erecting expensive hoisting and reduction works. Both of these subjects are more fully treated of in Chapter II., and mention of them is here made only to emphasize the impor- tance of extreme care in all these points. Just as an ounce of quicksilver if thoroughly mixed with a ton of sand will show its presence in every pound of the latter on washing, so a very small amount of free gold will make a big showing in a ton of broken white quartz. The writer has seen a dump on which free gold could be easily found but which gave a return of less than $5 per ton when milled. Coarse gold ores, though the prettiest of specimens, are exceedingly deceptive, and extreme caution is absolutely essential to safety. Gold is so easily extracted from the ore when native (free) that to ask for capital to develop prospects reported to assay $50, $100 and upward per ton is sure to excite suspicion in the minds of those acquainted with the subject, as with a donkey, a little water, a few pounds of quicksilver, and a fair share of patience and physical strength the owner of such a prospect can create his own capital, provided always that the assay represents the whole mass and not some individual specimen. Costly mistakes are also made through want of knowledge of the way in which ore is distributed through the vein. Experience has taught the writer that not a small proportion of those who might be sup- posed to be somewhat familiar with the subject imagine that a vein has a uniform thickness like a plank, and like the latter is made up of the same material throughout, so that there ought to be only two kinds of veins, those which never carry ore and those whicl} are continually in ore. Excessive antici- pations and undue depression result from such views, a diminution in thickness being never looked for on INTRODUCTORY. 13 the one band or an increased quantity on the other. Probably no vein carries ore from wall to .wall through- out its entire length. The probabilties are altogether against such a condition. The spotted character of most ore bodies is well shown in pi. 8, which is a copy of a longitudinal section of the Dolcoath mine (sometimes called Wheal Dolcoath) in Cornwall, Eng- land. The length on the vein covered by the section is about 3,300 ft. and the depth about 2,300 ft. The longitudinal elevation of the Comstock lode prepared by the writer for the U. S. Geological Survey shows vastly greater blank spaces. A want of knowl- edge of how ore occurs in veins has ruined many a mine. Intimately connected with this subject, which is treated at length when speaking of the structure of veins, is the change in the character of ore in depth from various causes, frequently resulting in the aban- donment of the mine on reaching the water level. Free gold ores may change into iron pyrites of a much lower grade, yet more costly to work, and rich copper ores may give out entirely, being replaced by low- grade iron pyrite carrying a small percentage of copper too lean to pay the cost of working. Failure may also occur from want of care in protect- ing the interior workings, resulting in extensive caves which may involve the loss of a shaft or an entire ore body by mixing it with waste from the walls and reducing its value below the limit of profitable extrac- tion. Even outside of coal mining such accidents are far from infrequent. Only those who have seen the evidence of the immense power developed by the pres- sure of large masses of earth, or even by its expansion under some circumstances, can realize its amount or extent. Both in coal and gold gravel mining the floor of a drift is apt to rise up or "creep," from the pres- sure of the surrounding mass squeezing Jbhe bottom upward into the space made vacant by the drift or tunnel. This occurs especially when the floor is soft 14 PROSPECTING AND VALUING MINES. (or as the gravel miners say, "cheesy"). In one in- stance in California the writer has seen a tunnel driven through the rim, or bed rock of a gravel chan- nel, as might be the lower tunnel in pi. 11, fig. 2, which, when it broke through into the channel, encountered a body of clay and gravel, so soft that it was squeezed by the weight above into the tunnel like a huge sau- sage, nearly as fast as it could be removed. In another case of a tunnel being driven to reach some old work- ings,the miners were furnished'with a grade-gauge by which to lay the track, so that with one end laid upon the older portion, the new sills could be put in as the tunnel progressed, on the correct slope to connect with the old workings. Owing to the creeping of the bottom during the progress of the work, each set of track timbers as it was laid was squeezed upward before the time came to lay the following section, and the tunnel came out much too high, and was a failure in consequence of thus having acquired too steep a grade. Finally, litigation resulting from defective locations is a fruitful source of trouble, involving a heavy tax. on the resources of the mine. Through a forgetful- ness of the importance of determining the direction of lode before making the location it sometimes happens that the lode passes out of the side lines into the prop- erty of adjacent owners, instead of extending the full length of the claim, and the mine not only loses a con- siderable length of the lode, but becomes involved in vexatious questions of boundary lines, the litigation over which may absorb all the revenues or even leave the mine in debt. Such are some of the causes which lead to failure of mining enterprises. They will be seen to be generally due to want of knowledge on the part of the prospec- tor, investor and managers of the enterprises of some special point in their respective capacities. It must not, however, be understood that all failures result INTRODUCTORY. 15 from this cause. There are cases where circumstances arise which could not possibly be foreseen and guarded against, and the judgment of the very best men may err, for we are none of us infallible; but it is desired to show that at least very great losses might be avoided if there were a more general understanding and appre- ciation of the fact that to be a successful mining man requires a combination of mental and physical quali- ties such as few other callings demand; and that min- ing is a business calling for special training just as certainly as technical knowledge is essential to the watchmaker or shipbuilder. The present chapter has been practically a presenta- tion of failure after failure, and these would be often laughable if the incidents were not so pathetic. The good faith of the men who made the mistakes quoted as samples was unquestionable, and only intensifies the pity felt for their misdirected energies. Fortu- nately there is a brighter side. The presentation has only been made out of abundant precaution. There is no more fascinating occupation in the world than min- ing; none that keeps all the faculties so fully alive, and no sensation so pleasant as the handling of the bullion after a successful run ! while it is not unlikely that the percentages of successes would prove as great as in most of the other great industries. CHAPTER II. WHAT CONSTITUTES A MINE. A MERE bunch of ore will not make a mine; and it may be well to examine the factors which really go to constitute a mine. A "mine/ 5 then, is any deposit of mineral which can be worked at a profit; that is to say, before the deposit is exhausted it must have re- turned to the "adventurers" (as the owners or operators are frequently called in England) the original pur- chase money, the entire cost of the improvements of every nature, and the entire cost of working the ore, whether it be mining, milling, smelting, transporta- tion, supplies, superintendence, or office expenses, together with a fair interest on the money invested. If we charge against the salable product all the ex- penses except purchase money and plant, we arrive at the running cost of production per ton, and if the selling price per ton be greater than this, the differ- ence per ton will go to the account of purchase money, development and plant; and there must be in the deposit at least a sufficient number of tons of ore, which, multiplied by the profit per ton, will extin- guish the original cost of mine and improvements, it being supposed that repairs to reduction or hoisting works, etc., are charged to the cost of producing and milling or smelting the ore. For instance, if the purchase money and original plant cost $200,000, and the profit per ton over ex- penses of production and reduction is $10 per ton, the mine must produce 20,000 tons,. at least, before it can WHAT CONSTITUTES A MINE. 17 be called self-sustaining, and a surplus over that amount to cover reasonable interest. If the ore be free gold quartz, or free-milling silver, about 13 cu. ft. in place will weigh 1 ton of 2,000 lb., so that the cubic contents of the 20,000 tons would be 260,000 cu. ft., equal to a block of ground 260 ft. deep by 1000 ft. long, if the vein be 1 ft. thick. 130 ft, deep by 1000 ft. long if the vein be 2 ft. thick. 65 ft. deep by 1000 f r. long, if the vein be 4 ft. thick. or, if the ore deposit be only 500 ft. in length 520 ft. deep by 500 ft. long, if the vein be 1 ft. thick. 260 ft. deep by 500 ft. long, if the vein be 2 ft. thick. 130 ft. deep by 500 ft. long, if the vein be 4 ft. thick. but if the ore shoot be only 100 ft. in length 2,600 ft. deep by 100 ft. long, if the vein be 1 ft. thick. 1,300 ft. deep by 100 ft. long, if the vein be 2 ft. thick. 650 ft. deep by 100 ft. long, if the vein be 4 ft. thick. From the foregoing it is evident that the length of the ore body is of immense importance, as the cost of working a mine increases with depth at a constantly increasing rate; and the longer the ore shoot, the shallower will be the workings to accomplish the same results. If the shoot be only 100 ft. long it will be necessary to sink ten times as deep, at a heavy ex- pense, as if it were 1,000 ft. Of course this is assum- ing a theoretical regularity of deposit. In order that similar calculations may be made on other classes of ore, the following table gives the specific gravity of the principal metals and their prin- cipal ores; the weight of 1 cu. ft. of each, and the number of cubic feet which will equal a ton of 2,000 lb. As the specific gravities of the ores are taken from pure specimens, generally crystallized, they will give, as a rule, quantities too small in the column of cubic feet per ton, as the ores in run-of-mine are seldom free from impurities; so that a somewhat 18 PROSPECTING AND VALUING MINES. greater number of feet should be assumed in making the calculation, to be on the safe side: SPECIFIC GRAVITIES OF METALS AND MINERALS. Metals and Minerals. Specific Gravity. Weight of cubic ft. Pounds. Number of cubic feet to ton. Range. Average. Gold Silver . 15.60-19.33 10.10-11.10 5.22-7.36 19.30 10.50 6.08 8.84 4.20 5.00 4.80 2.20 13.58 9.00 11.44 7.50 6.00 7.00 4.10 4.20 3.46 7.21 7.69 5.00 4.90 3.80 5.00 6.20 4.41 7.35 6.75 6.70 4.57 2.65 3.18 4.51 1.00 1206.25 656.25 380.00 552.50 262.50 312.50 300.00 137.50 846. (X) 562.50 715.00 468.75 375.00 437.50 256.25 252.00 216.25 450.00 480.00 312.50 306.25 237.50 312.50 387.50 275.62 459.00 421.87 418.00 285.62 165.62 198.75 281.87 62.50 1.66 3.05 5.26 3.62 7.62 6.40 6.66 14.62 2.36 3.55 2.80 4.27 5.33 4.57 7.84 7.95 9.25 4.44 4.17 6.40 6.53 8.42 6.40 5.16 7.25 4.35 4.74 4.78 7.00 12.08 10.06 7.01 32.90 Silver free ores Copper Copper pyrite 4.10-4.30 4.40-5.50 4.50-5.10 2.00-2.40 Copper purple Copper gray Copper silicate CinnrJbar 9.00 Lead Lead galena 7.257.70 5.40-6.47 Lead carbonate Zinc Zincblende 3.90-4.20 4.00-4.45 3.43-3.49 2jinc carbonate Zinc silicate .... Iron, cast Iron wrought . . Iron magnetite Iron hema ti te Iron limonite Iron pyrite 4.83-5.20 6.00-6.40 4.32-4.49 Iron, arsenical pyrite.. Iron chrome Tin Tin oxide 6.40-7.10 Antimony Antimony sulphide Quartz 4.52-4.62 Fluorspar 3 .01-3.25 4.30-4.72 Sulphate of baryta. .... Water But as we may frequently want the weight and bulk of ores made up of several minerals, the following ex- amples will show how the weight per cubic foot of such ores may be obtained : Calculation by Bulk. Take an ore containing say 50% of its bulk in galena, 25% in arsenical pyrite, 8% in zincblende, and 17% in quartz. By reference to the foregoing table we have : WHA T CONSTITUTES A MINE. 19 0.50 of 1 cu. ft. of galena = 234.37 Ib. 0.25 of 1 cu. ft. of arsenical pyrite = 96.88 Ib. 0.08 of 1 cu. ft. of zinc blende = 20.50 Ib. 0.17 of 1 cu. ft. of quartz = 28.15 Ib. 1.00 379.801b. Calculation by Weight. But if it be desired to ascertain the weight of 1 cu. ft. of ore containing the same minerals estimated by weight instead of bulk, we can calculate the bulk of a known definite weight, say 1,000 Ib., and instantly determine the weight of 1 cu. ft. by simple proportion. Out of the 1,000 Ib. we shall have : 500 Ib. galena -f- 468.75 = 1.068 cu. ft. 250 Ib. arsenical pyrite 387.50 = 0.645 cu. ft. 80 Ib. zincblende 4- 256.25 = 0.312 cu. ft. 170 Ib. quartz 165.62 - 1.026 cu. ft. 1000 3.051 cu. ft. - or 6.102 ou. ft. per ton. By proportion the Galena = 0.350 of 1 cu. ft. X 468.75 = 164.06 Ib. Arsenical pyrite = 0.212 of 1 cu. ft. X 387.50 = 82.15 Ib. Zincblende = 0.103 of 1 cu. ft. X 256.25 = 26.14 Ib. Quartz = 0.336 of 1 cu. ft. X 165.62 = 55.65 Ib. 1.000 328.00 All other combinations may be worked out by these examples. Assuming the profit on this class of ore to be the same as that of tile free gold ore given pre- viously ($10 per ton), it is clear that the ore body would only have to be about half the dimensions before quoted to secure the same results, as 1 ton only oc- cupies about half the space of the first illustration. Favorable Conditions. If the mine is so located that its product can be sold to independent reduction works, it is plain that smaller ore bodies may be profit- ably extracted; and yet smaller ones if the mine be worked by the original discoverers, and the ore is of a grade high enough to yield a margin of profit over the cost of extraction and transportation to market, as in the first case there are no reduction works to be paid for out of the profits of the mine, and in the latter 20 PROSPECTING AND VALUING MINES. case, neither reduction works nor purchase money. Any ore body fulfilling these conditions may properly be called a mine, and it is such that the prospector is looking for. Mining Compared with other Business. Only an exceedingly small proportion of the locations made ever develop into mines, probably not more than one in a hundred. On the Comstock lode, out of several thousand locations on record, less than fifty had any large amount of development, and still fewer ever paid dividends; yet the gross product of bullion from the comparatively few active mines was enormous. Simi- lar conditions hold good in most other mining camps; but it is likely that the percentage of success in min- ing enterprises is fully as great as in almost any other line of business certainly as great if the same amount of care has been exercised in selecting the property as is usual in opening a new store or hotel. But the miner must always remember that while the business of the store may expand indefinitely, he is from the very start living on his capital (the total amount of ore in the mine), and that this diminishes daily the more rapidly as the output is enlarged; while after reach- ing its extreme productiveness the later stages of a mine are merely like realizing on the assets of a fail- ing business. VALUATION OF MINING PROPERTY. The value of min- ing property is therefore not to be estimated by the amount of the dividends it may be paying at any par- ticular time, but by the number and value of the divi- dends it will be able to pay in the future. Relation of Profits to Price. Thus, because a mine has just paid an annual dividend of $1,000,000, it does not follow that the mine is to be valued at $10,000,000 (which would make the dividend equal to 10%), because it can only be worth that figure to pur- chasers for investment if it is able to disburse that amount or over in dividends in the future with a fair WHAT CONSTITUTES A MINE. 21 interest on the investment in addition. If the divi- dends were distributed over ten years at the rate of $1,000,000 per annum, the investors would just receive the original amount paid without interest, so th&t if the investors are to receive interest at the rate of 10% on the money invested, the mine must pay another $5,500,000 in dividends, making $15,500,000 in all, to be worth $10,000,000 as an investment. But it might be that the mine had reached its maxi- mum productiveness when it paid the million-dollar dividend, and the ore bodies in sight began to show signs of exhaustion. In such a case the extreme value to an investor would only be the actual profit on the exposed reserves, which might be small. The chance of finding new ore bodies cannot be expressed in figures. One of the great sources of dis- appointment in mining enterprises is the over-estima- tion of mining values, mistaking capital for profit. Another is the payment of unjustifiable prices, not only for properties with considerable development, but for holes in the ground or mere naked locations. It is true that very often the purchaser expects to sell again at a profit and not to work the property, but then he has removed his dealings from mining to the realms of speculation, and has no reason to grumble if failure follows the change. Ore "in Sight." Practically the value of a mining location is the net profit on the ore exposed. If there is any promise in the surroundings of a future to the location, this definition might possibly be enlarged to the gross value, the purchaser looking to developments made with his own capital for reimbursement of the original investment and profit. The value then of the majority of original locations is very small. Many of them are absolutely valueless, being made upon a mere stain or a slight difference in the color of a certain streak or layer of rock, or the presence of a little iron pyrite in a particular seam, which only means that 22 PROSPECTING AND VALUING MINES. there has been decomposition of some of the horn- blende or allied mineral contained therein. If, how- ever, there is actually valuable ore in sight, this must be carefully measured for length and breadth, and if these measurements show a continuous workable body the price of the location might possibly be the value of this ore to a depth of a few feet, according to the width of the ore exposed. The situation is improved by the sinking of a shaft or the running of a tunnel, but a single shaft does not prove the existence of much ore. It simply shows its presence at that particular point to a certain depth and the quantity in sight will be the two triangles a and b in pi. 13, fig. 1, multiplied by the average thick- ness. If two shafts have been sunk, as in pi. 13, fig. 2, we can call the shaded portion "in sight. " If the development be a shaft with drift from the bottom, as in pi. 13, fig. 3, we can still only consider in sight the portion shaded, with a probability of more because of the ore in the bottom of the drift c. The same will be the case if a tunnel is run on the vein as B in pi. 13, fig. 4, but if the bottom of the shaft A is in ore and the face of the tunnel B also, part of the block D may be added to the probable reserves (unless the ore is growing smaller in width), though it cannot be con- sidered actually in sight, by which we understand a block of ground exposed on all sides, as in pi. 13, fig. 5, where the blocks E E are actually in sight and DDD can be added as probabilities, along with an unknown quantity below the lower drift at F. In all the foregoing examples it is supposed that the outcrop is the extreme workable length of the ore, and that none of the underground workings have been run out of ore, so that we have no means of judging whether the ore body is holding its own in size, or increasing or diminishing; but if the explorations have developed the facts shown in pi. 13, fig. 6, we can afford to be liberal in the estimate of the probable reserves, as dis- WHAT CONSTITUTES A MINE. 23 fcinguished from ore in sight (shaded), because it is evident that the ore body is not at present diminish- ing in horizontal length, and may therefore be exten- sive in depth. If, on the contrary, the result has been as shown in pi. 13, tig. 7, we must be exceedingly con- servative, as the ore body is evidently pinching out downward as well as laterally. It would be easy to extend these illustrations, but enough has been said to show the basis on which esti- mates of quantity of ore in sight in a mine are arrived at, and also to show that work is the only thing which can give value to a location. Because a prospector has been able to make two or three locations or more, in a season's work, it does not follow that they are actually worth the time spent in securing them. The value of an article is not the price paid for it, or its actual cost to the owner. The price paid may have been out of all proportion to the value, or the actual cost of the article may have been so reduced by improved ma- chinery that it can be bought for a mere fraction of the Hum paid for the original production. So the value of a mining property is not to be estimated by what it has cost the parties offering it for sale, but by the profit it will realize to the purchaser. Grade of Ore. But even a large body of ore may be valueless if the cost of extraction and reduction equal or exceed the value of the metal extracted from the ore; nor does it follow that, because ore of a certain grade has been profitably worked in one mining camp, this will hold good for all others, as the conditions vary so widely. If everything in the shape of sur- roundings is favorable, a very low-grade ore may prob- ably yield a profit, while in another camp a much richer ore may bring the miners into debt. Sampling. Where no work has been done on a loca- tion which shows enough of an outcrop to justify a more extended examination, we can simply sample the croppings thoroughly to ascertain which portions of 24 PROSPECTING AND VALUING MINES. them carry mineral enough to be valuable, and the character of this mineral, because it is seldom that the outcrop is of uniform value throughout its length. This is not done by taking small hand samples here and there, for the most honest man is not honest enough to be able to select a fair average in such a way. A clean cut across the entire width of the pay streak should be taken at stated intervals, to avoid the interference of the judgment, or the deception of the eye, and each of these samples should be thoroughly broken on a clean floor, mixed, spread out in a thin sheet and quartered. One of these quarters should be broken still finer, remixed and again quartered. This will probably bring the sample down to such a size that its entire mass can be ground to coarse "pulp. " Assaying. From this pulp samples should be fur- nished to two independent assayers, retaining the balance for further tests should there be much differ- ence between the results obtained from the assayers (between whom there can be no collusion, as the look of the pulp will not betray any peculiar external char- acters of the ore by which its identity might have been suspected). To furnish both assayers with the same pulp is also fairer to the assayers, because they are both placed on the same footing, which is not the case when a piece of ore is broken into two pieces and one-half given to each (except in a few exceptional cases), as there may be sufficient difference in the composition of the two pieces, especially in a complex ore, to war- rant considerable discrepancies in the results obtained, which would naturally throw a shadow of doubt upon the entire investigation. In gold ores this is very liable to be the case. A small sprinkling of telluride of gold (looking like lead) might run one specimen up into the thousands per ton and the other give only tens. Care should be taken to distinguish between mere specimens and true average samples. In this way only can reliable results be obtained^ WHA T CONSTITUTES A MINE. 5 but if the ore prove to carry much gold, even then they will not be entirely satisfactory, nor will they indicate the true commercial value of the ore unless determination of the nature and quantity of undesir- able mineral constituents be made, if such are sus- pected from examination of the ore as taken from the vein. When gold is found only in combination with other minerals it is usually disseminated through them in such fine particles that the distribution is compara- tively uniform and an assay will be satisfactory, in so far as the amount of gold in the ore is concerned; but when a portion of the gold has become free, or liber- ated from the associated minerals (as the various forms of pyrites) by the decomposition of the latter, or still more so when a portion of it has never been in com- bination, but is scattered through the mass in particles of varying dimensions, the assays will be in all prob- ability valueless, because they may accidentally include quite a large piece of gold (comparatively speaking), and this multiplied by the thousands of times which an assay sample is contained in a ton would give very high results, while the next sample, not containing such a piece, may only show very small or insignificant returns. This may easily occur, as the gold cannot readily be ground fine enough to pass through the sieve with the other pulp, but must be mixed with the pulp after it is ground, and thus the chance of getting a fair average sample is exceedingly small. Horn Spoon. Every prospector should carry a horn spoon, made by cutting off the belly of a large cow's horn and polishing the inside with sandpaper, as in pi. 13, fig. 8; or he can obtain an iron one of the same shape, but having one-half galvanized to better show black ore minerals. Such a spoon cau be carried in the pocket, and if the presence of free gold in the ore be suspected a few minutes will suffice to grind up a 26 PROSPECTING AND VALUING MINES. sample on a smooth flat rock with a small hand stone, and wash it out in the nearest water hole, which can be very much smaller than is required for the gold pan, a bucket or even a wash basin being amply large enough. The very finest colors may be detected by this method. If any are found, a sample large enough to secure a fair average should be taken, and the entire mass reduced to pulp. All screenings which will not pass through the sieve should be saved until the process is complete, and then returned to the pulp, the weight of which while dry should be carefulb r ascer- tained. The pulp should then be mixed with water, adding sufficient quicksilver to amalgamate the free gold, and thoroughly worked over to insure complete contact of all the gold with the mercury. The amal- gam thus obtained may be reduced to a button with the blowpipe, care being taken not to inhale the mer- cury fumes, and then by simple proportion the amount of free gold per ton may be ascertained with reason- able accuracy, if the average of several tests be taken. Thus, if 5 Ib. of ore contain 25c., 2,000 Ib. will contain $100. Segregating Ore Minerals. An assay of the pulp which is left will give the amount of gold in combina- tion with the "sulphurets" per ton, and the sum of the two the total value of the ore. Also, by washing out the sand the percentage of sulphides per ton of ore may be ascertained, and an assay of these concen- trated sulphides will give the value of the concentrates per ton, and enable us to formulate a plan for their reduction. But if the ore contains a number of min- erals, such as iron pyrite, arsenical pyrite, zincblende and galena, we cannot decide on the best method until we have ascertained, by assay of pure samples of each of these minerals separately, which it is that contains the gold, or whether it occurs in all of them indis- criminately. In the case of smelting ores, such as galena com- WHAT CONSTITUTES A MINE. 27 bioed with zincblende, for instance, the presence of the latter being detrimental to the process, it is espec- ially desirable to know whether the blende carries any appreciable amount of the precious metals contained iu the ore, as the difference in the specific gravity of the galena and blende is so great (7.5 to 4.1) that the latter can be easily separated from the former during the process of concentration, and if valueless except as zinc, might be thrown away as a waste product, or reserved for separate treatment if in sufficient quantity to warrant such a course. If the gold is largely in combination with iron pyrite or other minerals which are easily decomposed by exposure to the action of air and water, the out- crop may yield a good showing of free gold in rusty quartz, stained by the oxide of iron derived from the pyrite, which may suddenly diminish in quantity when the permanent water level of the mine is reached, below which a large portion of the gold may be in combination with the unaltered sulphides. Usually such gold is very fine, almost if not quite like flour, but occasionally, as in iron pyrite from the slates near Fiddletown, Cal., the threads and crystals of gold may be readily seen, and felt projecting from the polished faces of the large cubes. Special Cases. In the case of ores containing native copper, the plan of taking a number of pounds and working it in the same manner as free gold is the only practicable way of getting fair results, and the same remark applies to those carrying native or horn silver, in fact to all ores containing minerals which will not pulverize and pass through the sieve; but ordinary assays are applicable to all other ores, provided care has been taken in preparing the samples by having them large enough and thoroughly mixed, so as to secure average results. Working Tests, Mill Runs, etc. As work pro- gresses, the accuracy of the results first obtained may 28 PROSPECTING AND VALUING MINES. be tested to some extent by actual working methods. The facility and cheapness with which this may be done depend upon the nearness of reduction works of a suitable character. High-grade ores can be shipped over trails on mule-back, to works at long distances from the mines, and even if the expenses consume all the returns the experiment will be worth the cost; but low-grade silver ores cannot be handled in this man- ner. Arastra. In the case of low-grade gold ores, in which the gold is free, which will not bear transporta- tion for long distances, good working results may be obtained from an arastra built on the ground, as it occupies only a small space and consumes but a small amount of water. The arastra consists simply of a circular floor made of large flat rocks carefully laid so as not to leave crevices of too large a size between them, inclosed by a low stone wall of suitable height, say 2 to 3 ft. In the center is erected a vertical spindle supported by a cross frame, to which spindle is fastened a long horizontal shaft, and beneath the latter cross arms to which large flat stones ("drags") are fastened by means of short ropes or chains. When a horse or mule is attached to the long shaft, and driven round in a circle, the cross arms drag the rocks attached to them around, and crush any ore which may be fed into the machine between themselves and the floor. Of course the amount worked daily will depend on the size of the arastra, and the softness or hardness of the ore, but it will do its work well and give a fair working test. Utility of Tests. By keeping the ore extracted from each 10, 20, or 30 ft. of the shaft or tunnel by itself, and working or shipping the batches separately, the miner will soon learn which portion of the ore body is the richest, and also whether it is fairly uniform in value, or changes frequently within short distances. A few such tests will soon determine the question WHAT CONSTITUTES A MINE. 29 whether it will pay to build a road to the mine, for the cost of such a road will ultimately have to come out of the mine. Roads. Without roads no heavy machinery can be gotten to 'the mine at anything like reasonable cost. Mining roads are often very costly enterprises owing to the rough and broken nature of the country which they must traverse, and the want of them not infre- quently greatly retards the development of otherwise promising mining districts. As all the locations in a new district must share equally in the benefits derived from a main road placing them in ready communica- tion with the outside world, the cost of the trunk road should be raised by an assessment on each location, made, by action of the mining laws of the district, a requisite to a legal title to the location. The lateral branches to the individual mines would naturally be built by the mines at their own cost. A mine opened by tunnels only will of course not feel the necessity of roads so promptly and keenly as one which is com- pelled by the nature of the ground to resort at once to shaft-sinking, as the former will be able to get along; with packages which need not exceed a mule-load in weight, except in the article of timber, but all require the roads sooner or later as a matter of economy even in provisions and supplies. PLANNING REDUCTION WORKS. Having then become satisfied that the ore body is large enough and rich enough to pay for its extraction, the character and size of the reduction works remain to be determined. Smelting. Should it be decided that the ore will be best reduced by smelting, it is doubtful whether the mine would be justified in erecting its own works, unless it is situated where purchases of various other ores can be readily made in considerable quantities, as few mines produce ore which may not be worked to greater advantage by admixture with other ores which can supply its deficiencies without adding barren 30 PROSPECTING AND VALUING MINES. material to the charge in the furnace. Ores rich in gold and silver, but poor in lead (usually called "dry" ores), may require rich lead ores to flux properly ; or ores with an excess of silica (quartz) may require the addition of lime or iron-bearing ores to accomplish the same result. It is from this circumstance that the great smelting centers, such as Denver, Swansea, etc., have arisen, which purchase everything which may be offered, and mix and work the ores to the best advan- tage ; each class of ore being kept separate in the yard. A furnace charge may thus be made up from four or five different kinds of ore, from widely separated locali- ties, the more refractory ores being added in small quantities .to those which work more readily. Concentration. It often happens in a vein that on one of the walls there may be a streak of solid mineral suitable for shipment as it comes from the mine, with no or only slight sorting, while the balance of the vein is filled with material in which there is so much waste as to render this impracticable; or the entire vein may be of this character. If the distance from the mine to the smelting works is great, and especially if any considerable portion of it be only trail or wagon road, it may not pay to send these poorer ores, as the whole expense including trans- portation might very likely more than equal the prod- uct. Such ores must be dressed to better grade by some method of concentration (usually by washing., more rarely by air or magnetic separators) if the re- sulting concentrates are rich enough to bear the cost of transportation; otherwise they may be valueless until the conditions of transportation are modified. Concentrates consisting largely of galena or heavy sul- phuretted silver ores may go to the smelter, but those made up almost entirely of iron pyrites, such as are obtained from many gold ores, may be retained at the mine, and worked by chlorination, if the daily prod- uct be large enough to keep a small reverberatory fur- WHAT CONSTITUTES A MINK. 31 nace for roasting in steady operation. These pyritous ores may also be made into a commercial product by matte smelting. The capacity of the concentrator should be propor- tioned to the output of the mine, just as the size of a stamp mill is determined by the same factor, and this output will depend on the size of the ore body and the condition of the development. Ore Supply Needed. -We frequently hear of a mine being ready for a mill when it has nothing more than a shaft 50 to 100 ft. deep, or a short tunnel on the vein. As an approximation we may say that a mine should produce 1 ton of ore daily for each of the men em- ployed around it, including blacksmiths, carpenters, carmen and outside help. There are of course mines where better than this is done, but these are excep- tional. We must therefore have room enough in the mine for a considerable number of men to be engaged in "stuping" ore and this involves a number of drifts or stopes, even for a small mill. If very active develop- ment is going on and the ground is easily worked, there might possibly be sufficient ore extracted from the face of the various headings, sinkings or upraises to keep a small mill going; but to depend on these would be bad policy, for the ore in several of them might "pinch" at the same time, and shut the mill down. Indeed, a mill should not be built until the ore body has been so thoroughly explored that it may be perfectly adapted to the requirements, both as regards size and character of equipment, as although it may be possible to find the money for experiments or mistakes, they must all ultimately be paid for by the mine and diminish the profits. Calculation of Tonnage Mined. To enable the pros- pector or miner to form a quick estimate of the amount of ore which he may be extracting daily from a drift, the following table will be found useful. Three kinds of ore are given as types. First, prac- PROSPECTING AND VALUING MINES. ideally clean galena; second, a concentrating ore; and third, ordinary gold quartz ore or free-milling silver ore, neither of which carry much heavy mineral. The yield in pounds is for 1 running foot of a drift 7 ft. high, and this figure multiplied by the number of feet run daily will give the daily yield in pounds, provid- ing there be no waste in saving the ore, as is usually the case in small seams, which are difficult to take out clean, especially if the ore is brittle or friable. DAILY ORE EXTRACTION PER RUNNING FOOT J DRIFT 7 FT. HIGH; VEIN VERTICAL. Class. Weight per cubic foot. Thickness of Ore. 3 in. 6 in. 9 in. 1 ft. 2 ft. 3 ft. 4ft 1 469 '"328"' 820 0.41 574 0.29 290 0.16 1641 0.82 1148 0.57 581. 0.29 2461 1.23 1722 0.86 871 43 3283 1.64 2296 1.15 11.62 0.58 6566 3.28 4592 2.30 2424 1.16 9849 4.92 9888 3.44 3486 1.74 13132 Ibs. 6.56 tons 9184 Ibs. 4.59 tons 4648 Ibs. 2.32 tons 1 2 2 3 166 3 The principle used in this table may be applied also to sinking shafts, thus: multiply the area of the work- ing face (if all ore, otherwise the area of ore seam only) by the number of feet sunk daily, and this by the weight per cubic foot in the table. For instance if we sink 3ft. daily on a 2-ft. vein and the shaft is 10 ft. long, then 10 X 2 X 3 X S28 = 60 cu - ft - X 328 = 9.84 tons, for ore of the second class; or if a drift be 6 ft. high on a 2-ft. vein and we run 2 ft. daily, we have 6 X 2 X 2 X 328 = 24 cu. ft. X 328 = 3.93 tons, To assist also in forming an estimate of the most desirable size for a null, the next table will be found useful, being applicable also to the required capacity of a concentrator. The duty of a stamp varies greatly according to its weight, the height of the drop and the number of drops per minute, the hardness of the ore to be WHAT CONSTITUTES A MINE. 33 crushed, the fineness of the screen through which the pulp must pass to escape from the battery, and the height of the discharge. In the case of many gold ores, in which the metal is very fine and the rock hard, 1| tons per stamp may be a fair day's work (24 hrs.), but when the rock is softer, or the gold coarser, it is not necessary to use so fine a mesh, and the dut3 T may run up to 2 tons daily ; while if the working of the ore is to be finished by grinding in pans, or the ore is exceedingly soft, a mill may crush still coarser and pass 2^ tons or over under each stamp in 24 hrs. The table is therefore arranged for each of those three capacities, and shows the amount of ore crushed an- nually, its contents in cubic feet and the area of the vein which would be extracted at various thickness. It is based on the ordinary gold quartz or free-milling silver ores (such as the ores of the Comstock), and 13 cu. ft. in the mine are considered to be a ton, as the result of determinations made on that lode; and 300 days actual running time in the year. If the mill runs more steadily the quantities must be proportion- ately increased. CAPACITY OF A 10-STAMP MILL. Class Ore ^ J,* 1 il Cubic ft. per ton. Equal blk. Tons. Consumption per diem, Consump. per annum (300 days.) t iN tons. 2 tons. 2^ tons. titi tons. 2 tons. 2^ tons. 1 165 13.0 1 15 195 30 195 20 260 40 260 25 325 50 325 4,500 58,500 9,000 58,500 6,000 78,000 12,000 78,000 7,500 Tons. 97,500 cu.ft. 15,000 Tons. 97,500 cu.ft. 1 2 328 6.5 2 2 AKEA OF VEIN EXTRACTED ANNUALLY. Duty of Stamp. Vein, 1 ft. Vein, 2 ft. Vein, 3 ft. Vein, 4 ft. Tons. 1U... Ft. 585x100 Ft. 292x100 Ft. 195xiOO Ft. 146x100 2 2 .:: 780x100 390x100 260x100 195x100 2V, 975x100 488x100 325x100 244x100 34 PROSPECTING AND VALUING MINES. The mixed ore is merely given as an illustration. In fact, as a concentrating ore, it would more likely be treated with rolls or other crushers than with stamps, the object in concentration being to keep the crushed ore in as large grains as possible, as the diffi- culties of concentration and percentage of loss increase with the fineness of the pulp. The table itself requires but little comment. While made up for only 10-stamps it can be modified to apply to any desired number but it emphasizes very strongly the desirability of long ore bodies, as it is evident that to get a year's supply from a tunnel on a vein 1 ft. wide, with a rise of the surface on the hill of 1 ft. in 2, we should have to follow the ore 484 ft. into the hill, and upwards 242 ft. to the surface at the end of the tunnel, as in pi. 13, fig. 9. If the ore shoot were only 200 ft. long we should have to sink on it or run another tunnel, either course involving an extra amount of dead work. If 100 ft. long only, we should have to sink 585 ft., attaining a depth of nearly 2,400 ft. in four years. If 200 ft. long, we should sink 1,200 ft. in the same time. As the cost of sink- ing and working m&in shafts is the heaviest item in mining, the length of the shoot, as before stated, is all important. Backs. In no case should the outcrop be consid- ered immediately available ore. About 50 ft. in depth, or at any rate a sufficient thickness to avoid caving, which will depend on the width of the vein and the condition of the walls, should be left as a pro- tection to the mine from surface water, for if the ore be extracted it is sure to leave a depression into which the snow and rainfall will drain, and find their way to the lower workings, to be subsequently pumped out at a heavy cost. These croppings will always remain an available asset, and should be the last thing taken out of the mine. DEFINITION OF A "MINE." To sum up then, a mine WHAT CONSTITUTES A MINE. 35 is a body of ore of sufficient size and richness to repay all costs of purchase money, erection of all necessary plant, dead work, extraction, transportation and re- duction, with good interest on the capital. Success will depend largely on a thorough knowledge of the sizo of the ore body as regards length, depth and thickness; the true character and composition of the ore; the adaptability of the hoisting and reduction works to the requirements of the property ; careful management by thoroughly competent men well up in the business; avoidance of mistakes and experiments, severe pruning of all unnecessary expenses, and the treatment of the mine as a business undertaking, and not as a gambling proposition. CHAPTER III. ROCK-FORMING MINERALS AND ROCKS. IT is not proposed to go further into this subject than to furnish a condensed outline of the composi- tion and structure of the principal kinds of rocks, those most commonly met with in connection with mineral deposits, so that the prospector may be able to recognize the most important of them. To describe all the different varieties would require a volume, and would be of no special benefit in this connection, as the distinctions are frequently founded on the pres- ence of some minerals of difficult recognition and quite secondary importance, and the descriptions would necessitate a much more extensive knowledge of mineralogy to make them intelligible than it is necessary for a miner to possess. ROCK-FORMING MINERALS. The principal minerals which make up the bulk of the rock formations are very few, and we shall find that when able to recognize quartz (or silica), feldspar, mica, hornblende and angite, there will not be much difficulty in giving a rock a name. Some of these names may really apply to groups of rocks, but in such cases the name of the group will be close enough. It is the different ways in which these five minerals are combined that distinguish the igneous rocks from each other; and it is the predominance of one or the other in the secondarj' rocks (or those which have been made out of the wear and tear of the igneous series) ROCK-FORMING MINERALS AND ROCKS. 37 which imparts to these secondary (or sedimentary) rocks their peculiar characters. Granite consists of quartz, feldspar and mica; sye- nite, of crystallized fedspar and hornblende; and basalt of feldspar and augite, with chrysolite or olivine, so that with specimens of these three rocks before us, or even in some cases with granite and basalt only, we are ready to study the characters by which the min- erals are to be recognized. The basalt used for refer- ence should not be so fine-grained that its constituent minerals are indistinguishable to the unassisted eye. Quartz is the glassy portion of granite which cannot be scratched with a knife. It crystallizes in the well- known form, the separate crystals being always six- sided prisms, terminating in a rather blunt pyramid with six sides or faces; so that the description will be: crystallizes in six-sided prisms (hexagonal) with six- sided pyramid for a termination; color, sometimes tinged with pale smoky or rose color, sometimes violet as in the amethyst, usually colorless and transparent or milky white; luster, vitreous (glassy); hardness, cannot be scratched with a knife, and itself scratches feldspar, glass, etc.; not acted on by sulphuric, nitric or hydrochloric (muriatic) acids. Feldspar is the white portion of granite which can be scratched with a knife. There are numerous varie- ties of feldspar, distinguished by their having either soda, potash or lime as one of their constituents in addition to the silica and alumina which are the essen- tial ingredients, but it is not easy to give differences which would be easily recognizable by the beginner in the study. The crystallized forms are usually white, more or less inclined to be transparent or trans- lucent in new fractures, but often weathering to a milky white. The feldspars in granites vary in color from white through pink to dull red, and often occur as seams of varying width running through the body of the rock. These seams are inclined to break into 38 PROSPECTING AND VALUING MINES. squarish fragments, showing the tendency of the crystals of this variety to have only four sides.- In many of the porphyries almost the entire mass is feldspar, the body of the rock being a kind of paste of uncrystallized feldspar, colored various shades of brown, green, pink, red, and purple, with scattered crystals of white feldspar, or transparent quartz, im- bedded in the paste, giving to it a spotted look. On decomposition of rocks largely composed of feldspar we have a series of clay formations, just as granites yield sand and sandstones. Mica is the mineral which in thin plates is often wrongly called isinglass (which is fish glue). In color it varies from colorless or white to black, through various shades of gray, brown, yellow, green and violet, the commonest colors being white, yellow, dark brown, dark green and black. While sometimes found in crystals of large size, they usually are quite small. The crystals are flat, six-sided, and invariably split into extremely thin plates parallel to the base of the crystal. When broken across the crystal, as is often the case in a rock fracture, the characteristic six-sided form may not be visible, but the thin plates separate easily into a brushy edge. These plates are elastic and can be bent considerably without break- ing, by which character the white varieties of the min- eral can be distinguished from the crystallized varieties of gypsum, which are also white and transparent and split into thin plates or laminae, but are brittle and break easily on bending. They are also destroyed by the action of heat, whereas mica is practically infusi- ble at ordinary temperatures, and is therefore used for stove fronts, etc. When a rock is broken the crystals may show with the flat side up, when they will appear as in a, pi. 13, fig. 14, but if the fracture cuts through the crystal the shape may be like b in the same figure, the edges of the thin plates showing distinctly. The colorless or white mica is called muscovite; the brown or black variety, biotite. ROCK-FORMING MINERALS AND ROCKS. 39 Hornblende occurs usually in small crystals, gen- erally black or greenish black. It is harder than mica and does not split into thin layers, which fact can be determined by the use of the knife. It very frequently crystallizes in little square columns like a in pi. 13, fig. 15, and sometimes in six-sided crystals, which may, however, be easily distinguished from mica by having two of the opposite sides much wider than the others, as in 6, pi. 13, fig. 15. Hornblende is not always crystallized. It often occurs in greenish or blackish masses with a fibrous or radiated structure, sometimes forming a rock almost by itself (horn- blende rock) and grades down into asbestos, which, has practically the same composition, and is only one of the uncrystallized forms of hornblende, of which there are many minor varieties, just as there are of mica. Augite is similar in appearance to hornblende, except that the crystals in cross section show eight sides, as in pi. 13, fig. 16, and is much less important than hornblende to the student of rock composition, until he has made some progress. We have thus two usually pale or white minerals, and three dark brown, ^greenish or black minerals to deal with, and a very small amount of practice will enable anybod.y to pick them out easily. The knife will tell the difference between quartz and feldspar, ' but mica, hornblende and augite are easily scratched with the knife, giving a colorless streak, and the dif- ference between the three minerals must be determined by the shape of the crystals. Many other minerals are associated with these, as small grains of magnetic or titanic iron in granites, forming the " black sand" of the miner; but they are not essential constituents, except in a few cases. Garnets, tourmaline, olivine, chlorite, chrysolite and apatite, the last four all green minerals, may occur in small grains or crystals, or may sometimes be so abundant 40 PROSPECTING AND VALUING MINES. as to give a distinct character to the rock, which may then be called a "garnet rock," "chloritic slate/ 'etc., as we shall notice later on. KOCK STRUCTURE. All rocks present lines of fracture, even though they were deposited as a solid mass, but some present a series of parallel planes along which they split with great facility, sometimes along the lines of original deposit, and sometimes nearly at right angles to the former. These fissure lines are known as stratification or lamination, cleavage and bedding planes, and it is highly important that they should not be confounded. Stratification is the result of earthy matter being deposited in water as layer after layer, with intervals of time between the deposition of the layers, during which the first layer deposited had time to harden or form a sort of crust which prevented it mixing freely with the succeeding layer and so on; so that the mass has become like a series of sheets of paper laid one upon the other, and when converted into rock by the lapse of time, and raised out of the water, the rocks split easily along these lines of deposit. The layers may vary greatly in thickness, depending on the amount of sediment brought down by the stream and the length of the flood periods. It is easy to understand that a stream during flood will carry immense quantities of matter into a lake or the ocean, becoming clear during periods of drought, thus fulfilling the conditions called for; and that such streams as the Mississippi, Amazon and Ganges may form beds of vast extent, while others may be limited to the area of a small lake. Eocks formed in this manner are known as sedimentary or stratified rocks. Cleavage. Certain rocks, such as roofing slates, while belonging to the stratified series, have become so altered by pressure that they no longer split along the lines of stratification or deposit, sometimes known ROCK-FORMING MINERALS AND ROCKS. 41 as "lamination lines" (a term applied to the thinner strata), but on a series of joints which have been sub- sequently formed by this pressure, generally more or less at right angles to the lines of the original deposit. The old lines of lamination are obliterated, and this new series of joints is much more numerous than the original horizontal planes, and the splitting character much more perfect, dividing the rock into very thin sheets. This structure is known as "cleavage. " It is more or less developed in coal beds and is there known as the * 'cleat," and is the cause of the coal breaking into small pieces when mined. In crystals of minerals the cleavage is the line on which the mineral splits most readib r , and is usually parallel to one of the smooth faces (facets) of the crystals. This is well illustrated in mica and gypsum. Bedding Planes and Strike Joints. In addition to these splitting planes, all rocks (even limestone and eruptive rocks) have acquired two or three sets of joints, more or less at right angles to each other, which divide the mass into large blocks and greatly facilitate the labor of thequarryrnan, who takes advan- tage of them in his mining operations. These may be altogether independent of stratification, being the result of the upheaval and compression of the earth's crust, though in some cases they may follow some of the more or less horizontal lines. Upon their char- acter frequently depends the shape of mineral veins and deposits. The joints which are roughly hori- zontal, or parallel to the original stratification, are called "bedding planes" or "dip joints," and the series running with the general trend of the rocks through the country, the "strike joints." These joints may be very numerous or wide apart, and are the cleanest cut in close fine-grained rocks such as limestones, where they are not obscured by the stratifi- cation planes, and also in some granites, furnishing fragments of all sorts of angles. These joints may be 42 PROSPECTING AND VALUING MINES. only a few yards long, or may extend for a mile, the latter feature being most prominent in close-grained rocks which have suffered comparatively little dis- turbance. A little thought will show why building stones should be put into the structure in the same position that they had in the quarry, that is, laid ac- cording to their " bedding," being stronger in this way than any other and less liable to scale off, on exposure to frosts and the acids in the rain water of cities. Metamorphixm. All rocks are constantly changing their character. The mud banks of to-day will be the shales and slates of the far future, and our sand banks, the sandstones of a coming era. In the same way and by the same agencies of time, moisture, pressure and heat, many of the older sedimentary rocks have lost much of their original character. The sand- stones have become massive quartzites, in which the small grains of quartz which compose the sand- stone are no longer visible; and the slates and shales have lost many of their lines of stratification, besides suffering other changes which have imparted to them a new common character, known as "schistose. " Such rocks are called schists. It is sometimes a very hard matter in a hand specimen of these rocks to determine by the eye whether it belongs to the metamorphic or eruptive series, so extensive have been the changes, and only the microscope, or a dis- tant view, when the main features of the mass alone strike the eye, can settle the question. (When the microscope is used in the determination of the rocks, a flake of rock is ground down so fine that print can be read through it, and it is this film that under the microscope tells the story of its origin and composi- tion). By reference to pi. 2, fig. 3, the difference be- tween the structure of slates and schists will be better understood* The upper part of the figure represents a slate rock (let us say one in which there are numer- ous fragments of hornblende by way of illustration, UOCK-FORMING MINERALS AND ROCKS. 43 otherwise a hornblende slate) and the lower part a schist having the same composition, called a horn- blende schist. In the latter there has been such are- arrangement of the particles that though the mass retains some traces of stratification, in the parallelism of its bedding planes, it has lost the smooth lamination planes, and consists of a series of plates, thickest in the middle and thinning out all round like a flat lens, the result being a very characteristic appearance (known as "foliated''), in which only a few of the lines of stratification have been preserved, although the process has not been such as to produce clean-cut cleavage. The result has in most cases been to toughen the rock, felting the constituents together, and few are more difficult to handle than this same hornblende schist, as it will not split and is much less brittle than most eruptive rocks. In these metamor- phic groups the changes have usually been so great that all traces of fossils have been destroyed, and their geologic age can only be inferred from their associa- tions. They are abundant in volcanic regions and largely associated with mineral deposits. Their ulti- mate condition when metamorphism is complete, ap- pears to be a return to a rock in which all trace of its sedimentary origin has disappeared and which cannot be distinguished from those which we know to have had an eruptive origin. The term metamorphism is not applied to the simple hardening of muds into slates, or similar processes, but only to those changes in which a rearrangement of the particles has pro- duced a rock with a decidedly differing appearance. CLASSIFICATION OF HOCKS. Rocks may be divided into simple and compound, the first class including those which consist essentially of one mineral, such as some limestones, gypsum, rock salt, and serpentine; the second including those which are made up of a combination of several dissimilar minerals. 44 PROSPECTING AND VALUING MINES. The simple rocks resolve themselves into two groups, the first of which consists of chemical precipitates, and the second of organic structures. The compound rocks resolve themselves into what may be called the "original" group, consisting of those of eruptive or volcanic origin, which are again divided into the "plutonic" and "igneous" series, the former term being applied to those rocks which have been intruded from below without reaching the sur- face, and the latter to those which have been ejected as lava from volcanic vents; and the "secondary" group, which is made up of rocks derived from the wear and tear of all other rocks previously formed, whether original or already secondary. This group may be divided into the "stratified" rocks which have been deposited in layers by the action of water, and those which are the result of volcanic outbursts other than lava, and which may be termed "fragmentary." The stratified rocks are again devisible into the simple and metamorphic sections. The boundary lines between all these groups are very poorly defined, and they can only be taken as gener- alizations. Thus many limestones may contain so much sand and clay, along with their fragments of coral and sea shells, as to be almost a compound rock, but they largely lack the stratified character, while in the compound rocks many which have been ejected from volcanoes also occur in situations where they have obviously never been exposed to the atmosphere at the time of their formation, as the basalts in the coal beds. The following tabular presentation will show the general arrangement in a compact form : BOCKS CLASSED ACCORDING TO ORIGIN. A. SIMPLE ROCKS. I. Chemical Deposits such as some limestones, rock-salt, gypsum, serpentine. II. Organic Deposits such as some limestones, chalk, infusorial-earth, coal, etc. ROCK-FORMING MINERALS AND ROCKS. 45 B. COMPOUND ROCKS. I. Original group: 1. Plutonic series such as granite, syenite, etc. 2. Igneous series such as basalt, trachyte, etc. II. Secondary group: 1. Stratified Rocks: a. Simple such as shales, sandstones and conglomerates. b. Metamorphic such as quartzite, soapstone, schists, etc. 8. Fragmentary Rocks such as breccias, volcanic tufas, and glacial deposits. SIMPLE BOOKS. As the limestones fall within the limits of both the divisions of this class no attempt will be made to treat the sections separately. Rock salt and coal are very important commercially, but the lime rocks from the great bulk of this series, either as sulphates (gypsum) or, more commonly, as carbonates (limestone, calcite). The great mass of limestone has been segregated from sea water, into which it has been carried by the streams which have dissolved it from the rocks through which their waters have per- colated. Limestones proper vary in hardness from very soft to quite hard rocks, compact and usually close-grained in structure, ranging in color from white through shades of yellow and drab, to blue and even black, and consist essentially of carbonate of lime, which effer- vesces on the application of acids; and they may con- tain so many impurities, such as clay, sand, etc., that they become unsuitable for the manufacture of quick- lime for building purposes. This arises from the varying conditions under which they have been formed, and which determine their character. A large portion of them consist of the rocky skeletons of corals or the shells of minute animalcules. Chalk consists of the minute shells of a vast group of small animals called Foraminifera, which live in sea water in countless millions. These extract the carbonate of lime, which forms their shells, from the sea water, and when dead they fall to the bottom forming a soft ooze, which if exposed to view in future ages would be the same as chalk as we know it. These 46 PROSPECTING AND VALUING MINES. shells are so minute that only a powerful microscope can show their forms, and it takes millions of them to form a cubic inch of rock. The purer forms of chalk are soft, white and earthy, but time has wrought such changes that some of its varieties become more and more compact, until they grade into limestones, and the organic formations have had their constituents so modified that nearly all trace of their organic origin has disappeared, and they can scarcely be distin- guished from the granular crystalline chemical deposits. Flint, which is a form of silica, occurs in the chalk beds, and has probably been formed by the separation of small quantities of silica from some of the organic remains, by percolating waters, and its concentration into rough nodules of very compc^ct structure, usually dark or blackish in color, and resembling horn or glass in thin fragments. Coralline Limestones. Immense deposits of lime- stona have been built up by coral insects, like the reefs so common in the warmer seas of the world at present, and these usually contain numerous fossils which stand out more or less prominently on the surfaces of the rock which have been weathered by the action of air and water, though they may be indistinguishable on a freshly broken surface. This probably arises fom the greater solubility of the uncrystallized portions of the rock. Other deposits have been made up of broken frag- ments of coral detached from the main reef, and washed upon the adjacent beach, where they have been mixed with sand and broken sea shells,forming beds with many impurities. Besides these, there are compact beds which appear to have been chemically deposited. To this section also belong those deposits made by hot springs which deposit the excess of lime held in solution on cooling as "sinter," a term applied to all such formations, ROCK-FORMING MINERALS AND ROCKS. ^ whether formed of lime or silica. If made of the former, they are known as <( calcareous sinter/' if of the latter as "silicious sinter." Limestones for making quicklime should be free from silica. When this is present in considerable quantities, it not infrequently makes itself visible on the weathered surfaces, imparting to them a peculiar dry harsh feel, the lime wearing away more rapidly than the silicious portion, which is thus left in relief on the exposed surfaces. These silicious limestones and those carrying clay or alumina, which are not suitable for the production of ordinary lime, are util- ized in the manufacture of hydraulic cements. Marble is a variety of limestone in which the entire mass has become highly crystalline. The finest varie- ties are as clear and even in grain as lump sugar. In colors there is an infinite variety, many kinds being often found in the same belt. Freedom from iron min- erals (which will rust and stain the dressed slabs), purity of color and closeness of grain are the chief elements in determining the value of marble, but cheap transportation to market is essential to the successful opening of a quarry, however good the stone may be. Dolomite is a magn-esian limestone, consisting of the carbonates of lime and magnesia, usually of a crystal- ine texture and yellowish tints ; and while some bodies appear to be original chemical precipitates, others are undoubtedly ordinary limestones which have been changed by the percolation of magnesian waters. Both the ordinary carbonate ol lime and the magne- sian variety are used as fiuxes in the smelting of iron and lead, but all limestones are not of equal value for this purpose, any more than they are for quicklime. A chemical analysis or practical test must determine their value for both purposes. Magnesite in composed of carbonate of magnesia, and is much less common than limestone or dolomite. Limestone crystals (calcite, calcspar) are often mis- 48 PROSPECTING AND VALUING MINES. taken for quartz, and as it is a frequent accompani- ment of metallic ores, the chief differences are worth noting. In crystallized limestone the characteristic shape is rhomboidal ; that is, the crystals are four- sided, but none of the angles are right angles, while each pair of sides is parallel. When crystallized in pointed forms with six sides, the crystals are like pyramids, without the straight portion seen in quartz, and the apex is more pointed. This sharp-pointed character has given it the name of "dogtooth spar. " In addition to these differences it is much softer than quartz, being easily scratched by the knife, and splits easily along the line of cleavage. Carbonate of lime (calcite) is not likely to be mistaken for any other mineral than quartz except feldspar and gypsum, and from these it may be distinguished by the action of acids, or by the fire test to ascertain if it will form quicklime. This will set slowly, whereas burnt gypsum forms plaster of paris and sets promptly when mixed with water, but does not become as hard as the cements made by calcining silicions limestones. Gypsum (sulphate of lime) differs from the carbo- nate in that it does not effervesce with acids. It is valuable chiefly as the source of plaster of paris and as a manure, the latter consisting simply of the raw pul- verized rock. Gypsum crystallizes in white translu- cent masses which scratch very easily and split into thin non-elastic flakes, which may sometimes be ob- tained of great size; this form is known as Selinite. Fibrous, very silky varieties of gypsum are known as "satin spar;" and the close-grained forms, when of even texture and finely crystalline, are distinguished as "alabaster," Infusorial earth resembles chalk in appearance and general constitution, being made up of the skeletons or shells of minute organisms, but the term is gener- ally applied to those which consist of the scales of little vegetable organisms called "diatoms." These ROCK-FORMING MINERALS AND ROGK8. 49 are made of silica instead of lime, and consequently the rock is not acted on by acids. The excessive fine- ness of the powder derived from crushing these earths, and the hardness of the individual particles, make them very useful for polishing powders, which are known commercially as "tripoli," "electro silicon," etc. Serpentine is essentially a hydrated silicate of mag- nesia, and is a dark blackish-green rock, with very smooth slippery joints, generally highly polished and variegated with greenish or yellowish films, like soap- stone or French chalk such as is used by tailors. The more brilliantly colored varieties are used for orna- mental stonework, under the French name of "verde antique." While. some serpentines have been original deposits on the sea floor, others have been in all prob- ability intruded masses of eruptive rock, containing olivine, which have undergone extensive metamor- phism and assumed their present aspect. COMPOUND BOCKS, ORIGINAL GROUP. Instead of de- scribing these rocks under the two series named in the table, which is based on their origin, and often calls for extended investigation to determine to which series any particular rock should be referred, it will be sufficient to here classify them by some striking physical peculiarity which is easily recognizable by everybody. Three distinct forms may be recognized: (1) Those which are entirely crystalline, or made up of a mass of crystals each of which is distinct; (2) those in which a certain portion of the crystals are scattered through a "paste" of feldspar, which is very compact and does not show any distinct structure; and (%) those which do not show any signs of crystallization, but are of the same character throughout. It must be understood that this arrangement is purely arbitrary, as it separates closely allied forms; but it possesses the great advantage of being appli- 50 PROSPECTING AND VALUING MINES. cable without the use of the microscope, which is es- sential to any scientific classification. In this place the object is simply to enable the miner to find out the approximate name of any particular rock with the smallest amount of trouble, and not to educate him for an expert petrologist. Only the most characteris- tic of these rocks will be described. In the crystalline rocks the size of the crystals does not change the name of the rock. The size of the crystals may be said to merely indicate the rate at which the mass of rock cooled, and the amount of pres- sure under which the cooling took place. If an ejected lava cools very rapidly there is no time for the particles to arrange themselves in any particular man- ner, and the product is a rock which has all the ap- pearance of the slag from a smelting furnace. If the rate of cooling has been slower we have a crystalline rock in which the separate crystals are small; and if the cooling has been excessively slow we may have large and well-defined crystals, there having been ample time for a complete arrangement of all the con- tents of the rock into their respective kinds, according to the proportions of the various constituents and their relative affinities. "While this may be stated as a general proposition, it must not be taken as an abso- lute rule, as it may be varied by the more or less easy fusibility of the different minerals varying the proc- ess. These rocks vary greatly in their mode of forma- tion, though they all agree in their comparatively deep-seated origin. As they are intimately connected with the great changes in the earth's crust, and prob- ably owe their fusion to the heat developed by the immense pressure and friction incident to these changes (and perhaps by chemical action), it is not surprising that we find them chiefly in those localities where these changes are most activeb r at work, namely in the great mountain ranges. They may be found as great bosses or as dikes which have been squeezed into -HOCK-FORMING MINERALS AND ROCKS. 51 the rocks from below while in a plastic or semi-fluid condition, as in the case of some granites (pi. 5, fig. 5) or of the trachytes shown in pi. 5, figs. 1, 2 and 4. In the latter case the force exerted was not sufficient to break through the crust of overlying rock, but was sufficient to lift a portion of the surface into the form of a dome, the space thus formed being filled with the molten rock, a portion of which through smaller vents found its way in the horizontal layers of the sedi- mentary rock, forming beds between them, just as the basalt lava has found its way into coal seams, as shown in pi. 5, fig. 6, and between the shales as in pi. 5, fig. 3. In these figures No. 4 shows the theoretical structure of such a lava mass, showing the pipe a through which the lava (black) was seeking an outlet, and the lava forming a solid mass with branches pene- trating the overlying strata, and forming thin beds between them. In fig. 1 we have the top of such a mass exposed in the side of a canon, of which a b is the bed, with the strata (partially worn away) curving over the solid lava; while in fig. 2 we have an actual cross section through a mountain formed out of such a block, the solid lines showing what remains in place, and the dotted lines the original shape of the portion which has been removed, a being the bed on which the lava (black) spreads out, and b the shales, between the layers of which thin sheets of lava found a lodg- ment, as shown by the alternating outcrop of c, c. In 'fig. 3 we have similar horizontal beds of lava c, pene- trating the strata as offshoots from the dike d, but the lava at c is evidently only the remains of a similar sheet from which the superincumbent strata have been worn away, and not an outflow in the open air, because remains of other lava sheets are found above other strata at higher levels, as at e. In fig. 6, a, a, are shales, b coal, and c basalt, the latter intruded into the coal bed through the dikes d, d. In this case the coal is destroyed and the lava, originally black, has 52 PROSPECTING AND VALUING MINES. been altered to a whitish rock by the action of the coal on the cooling lava. In other cases the lava has forced its way to the sur- face, through the fissured rocks, and overflowed from the dike in immense sheets, or has been ejected from volcanic cones in huge streams, which have traveled many miles, filling up valleys and even continuing their course under the sea. Similar eruptions take place on the sea floor. Volcanic eruptions are also fre- quently accompanied by the formation of vast fissures on the flanks of the mountain which become filled with lava, and all these exhibitions of deep-seated heat pro- duce profound changes in the rocks which they traverse, the heat of lava streams being preserved for many years after all volcanic activity has ceased, so slowly do they cool when once crusted over. It is thus evident that the same body of lava may cool under very different conditions, and these have more or less effect on the appearance of the rock, so that the determination of the different kinds is often a matter of difficulty even to experts. ORIGINAL COMPOUND ROCKS, FIRST GROUP (wholly crystalline). Adopting the simplest though arbitrary classification for the sake of convenience, and disre- garding for the present purpose differences of origin, the compound "original" rocks (including both plu- tonic and eruptive rocks) of the first group embrace such species as granite, syenite, felsite, elvanite, trachyte, basalt, etc. Granite is a mixture of quartz, feldspar and mica. It may be either fine-grained or coarse, and vary in color according to the color of some one of its constit- uents. If the mica is white, we have a nearly white or light-colored granite; pink and red granites take their color and names from the tint of the feldspar, just as very dark or even black granite results from the abundance of black mica. When the feldspar is white and mica black in moderate quantities we have HOCK-FORMING MINERALS AND ROCKS. 53 various tints of gray. It is often traversed by dikes of younger age, usually paler in color and more com- pact than the rock which they cut; and though called the oldest rock, it is frequently found as veins (con- nected with the main mass) which penetrate both the stratified and unstratified rocks above it (as shown in pi. -5, fig. 5), which are usually much altered thereby. Granite belongs to the group of rocks called "plu- tonic," which have not broken through the surface of the earth's crust, but have consolidated at some depth beneath it. Sometimes hornblende is present in small quantities along with the mica, when it may be termed hornblendic granite, on the principle of using as a descriptive adjective the name of any peculiar mineral present in a rock but not essential to its composition. Granite seems to be the underlying rock of the entire series, and if this be the case it is not strange that all the rocks which have been derived from it should show a tendency to return to it, in appearance and composition, during the lapse of time, through the agencies of heat and pressure. Felsite, felsite-porphyry and elvanite are crystalline mixtures of quartz and feldspar, usually so intimately mixed that in felsite the crystallization is scarcely vis- ible, while elvanite is more distinctly granular. The latter rock is of frequent occurrence in the mining dis- tricts of Cornwall, and the dikes of it are known by the miners as"elvans," from which term the scientific name of the rock has been derived. Trachyte and Rhyolite. In many respects trachyte resembles granite, but may be easily separated by the feel of a fresh fracture, which is exceedingly sharp and rough, suggesting the surface of a cat's tongue. It occurs as dikes and large eruptive overflows, belong- ing to the series of modern lavas. In color the rock has a wide range of variation from gray to pink and brown. In composition the feldspar predominates over the quartz and is usually accompanied by horn- 54 PROSPECTING AND VALUING MINES, blende, mica or augite. It may be considered the modern equivalent of the older granite, but differing from the latter in being a volcanic product. Ehyolite is another rock so closely related to trachyte that the beginner will find it hard to separate them. As the mode of occurrence and general associations are entirely similar to trachytes, the distinction is not of essential consequence Syenite, The foregoing rocks have quartz as an essential constituent, while in syenite and basalt it is absent as free or visible quartz, or nearly so. For- merly syenite was considered a crystalline mixture of quartz, feldspar and hornblende, but the term is now used for a rock made up of crystalline feldspar and hornblende, with mica as an accessory or accidental mineral. In appearance it strongly resembles granite (but the knife will show the absence of quartz), and occurs in much the same way. The feldspar has a different composition from that found in granite. Basalt is the last of the wholly crystalline series which need be noticed here. It is usually a very dark, blackish, fine-grained rock, consisting of feldspar and augite, with a variety of associated minerals, such as olivine, occurring as small olive-green grains, of which the oxides of iron and manganese form about 15% of the mass, making the rock unusually heavy (sp. gr., 2.95). It has been ejected from modern volcanoes in immense quantities, covering hundreds of square miles in the States of Washington and Oregon, the suc- cessive eruptions or overflows from dikes forming a series of layers, resembling strata, and having in the aggregate an immense thickness. It is also the rock now being ejected by the volcanoes in the Hawaiian Islands, and, from its fluid character when molten, forms perfect rivers. It was such lava streams which filled the mountain-valleys of California and covered the gold-bearing gravels during the second outbreak, as the trachytes had previously done at a much earlier ROCK-FORMING MINERALS AND ROCKS. 55 period. When cooled rapidly, as on the surface of a new outbreak, it becomes full of bubbles formed by the expansion of the steam contained in the lava (to which it owes its fluidity), and it is in these cavities that opals, calcite and similar minerals have been formed by percolating waters. The porous lavas, with the bubbles so filled, are known as amygdaloids (from a word meaning almond). Below the surface the pres- sure has prevented the expansion of the steam so per- fectly, so that the bubbles get smaller and smaller till the mass becomes perfectly crystalline. Very fluid lavas may be so filled with these air, gas, or steam cavities that they look spongy and will float on water as "pumice stone, " or they may be drawn out by the violent winds eddying round the crater into fine threads like spun glass, in which form they are known as "Pele's hair, " Pele being a goddess associated with the Hawaiian volcanoes. Basalt frequently crystallizes into a columnar structure, the pillars being five or six- sided, with ball-and-socket joints. This columnar structure is always at right angles to the sheet of lava, so that in dikes they form more or less horizontally from wall to wall, and in overflows more perpendicularly. SECOND GROUP (porphyritic). In this group we have quartz-porphyrj r and a whole series of other por- phyries in which visible quartz ^is absent and which for the purposes of the miner we may designate simply as '"porphyry," using the term as a general one. Quartz-porphyry or dacite consists of a paste of feldspar which shows no sign of crystalline structure, the color of which may range from dirty white to pink, purple, brown or slate-graj'. In this paste are scat- tered small grains of transparent quartz, making a very characteristic rock which occurs in large masses, the rock belonging to the series of old lavas. It is largely developed in the Comstock mining region. Porphyry. Under this head may be classed all the rocks in which the paste just described contains dis- 56 PROSPECTING AND VALUING MINES. tinct crystals of feldspar, giving them a spotted appear- ance. They may contain mica, hornblende or augite as an additional mineral, and it is the presence of these,alorig with differences in the composition of the feldspars, which constitutes the basis for a new name. They occur as dikes, veins, intruded sheets, or as surface deposits, and include such species as porphy- rite, diorite or greenstone, andesite, phonolite or clinkstone, etc. THIRD GROUP (non-crystalline). In this group we have pumice stone, already described, and as the prin- cipal rock Obsidian, which is a lava cooled very rapidly, look- ing like coarse bottle glass, and hence frequently called ''volcanic glass/' It is of various shades in greenish black, black or red, and the red varieties are sometimes marbled with black streaks which are drawn out in the direction of the flow of the lava stream while 3'et in a pasty condition. It is not pretended that the foregoing descriptions are absolutely scientific. To lead the miner into the mysteries of orthoclase, plagioclase and triclinic feld- spar would be to hopelessly bewilder him ; yet many of the distinctions between the various eruptive and intrusive rocks are based on the one or other of these feldspars being the predominant component. The use of a powerful microscope is often necessary to settle disputed questions, and all rock-students know how many of these there are. If the descriptions will enable a person to distinguish a granite from a por- phyry, a felsite from a basalt, or a trachyte from a quartz-porphyry, they will serve their purpose; in- deed, they would almost do so if they will separate an eruptive or volcanic rock from a schist, and a schist from a shale. The student who once begins to take an interest in rocks will soon discover that their varieties are almost infinite, but that they resolve themselves into a few tolerably well defined groups, and will in- ROCK-WORMING MINERALS AND HOCKS. 57 evitably be led to examine into their differences and perpetually to ask himself the reason why. When the eye is -thus trained it is time enough to name these slighter differences, which are puzzling enough to expert observers. A general term for many of these eruptive rocks is "trap," from a Scandinavian word meaning steps or stairs, in allusion to the forms in which they often "weather." This weathering, a term applied also to the changes which take place on the surface of rocks exposed to the destructive action of the elements, is sometimes of great assistance in determining the true character of the rock, especially in those with a fine grain and dark color, as the feldspar on exposure, instead of retaining the glassy look which it may have in the mass (making it hard to recognize), becomes milky white and shows distinctly on the surface of the bowlders, even though in a clean new fracture the latter may be nearly uniform dark bluish-gray or almost black. In other cases the outer surface may be pitted with little angular holes from which the crystals have been dissolved, thus readily separating the rock from the stratified series to which it may otherwise have much resemblance. If depending on the pitted surface, however, care must be taken to ascertain that the pits are not "casts" of crystals of iron pyrite, as this mineral is abundant in all rocks whether eruptive or stratified, especially so in the former when decompo- sition of the mica or hornblende has set in. SECONDAKY COMPOUND BOCKS, STRATIFIED SERIES. The character of the rocks which are in process of decay and are being swept into the smaller streams and thence through the rivers to the ocean, plays an im- portant part in the formation of soils and the sedi- ments carried away by water and deposited to form rocks. If granite were the only rock being worn away by a stream, and the disintegration were complete, we should have clean deposits of sand and clay full of 58 PROSPECTING AND VALUING MTNE8. mica and hornblende. But when the stream began to cut into other rocks there would ensue a change in the character of the deposits, which would become yet more strongly marked if the destruction of the rocks had extended into groups already stratified. It is, therefore, easy to see that the conditions surround- ing the format! jn of stratified rocks are very complex, and we must look for great local differences even in rocks made at the same geologic period. So great is this difference at times that it would be impossible to place many rocks in their right chronological order if it were not for the fossil remains with which they abound, so that the prospector should religiously pre- serve all such fossils as he may find, or take such a note of the locality that he may direct others to it. The ultimate analysis of the foregoing compound original rocks gives approximately the percentages shown in the following table, compiled from Geikie, from which it will be seen that they resolve them- selves into three groups chemically. The large per- centage of iron and manganese in the porphyries and basalt is largely due to the presence of grains of mag- netic iron in the porphyries, and the oxides of iron and manganese in the basalt. CHEMICAL COMPOSITION OF ORIGINAL COMPOUND ROCKS. Silica. Alumina . Lime. Iron, Man- ganese, etc. Potash. Soda. Magnesia Granite. % 72 % 15 % 1 6 % 2 2 5 1 2 8 0*3 Quartzite Syenite 77 60 13 17 0.7 4 4 1.1 7.0 4.3 6.6 0.7 2.4 1.0 2.6 Trachyte Porphyries . . . Basalt 60 53 45 17 16 15 3.5 6.3 10.5 8.0 14.0 15.0 5.0 1.3 1 5 4.0 2.2 3 5 1.0 6.0 6 5 The potash, soda and magnesia, being soluble, are carried away on decomposition, and form the alkaline matter which accumulates in lakes without outlets, ROCK-FORMING MINERALS AND ROCKS. 59 such as Walker, Mono, Pyramid, and other lakes in the Great Basin between the Sierra Nevada and Rocky Mountain ranges in the United States, giving them their intensely saline character if the rocks furnishing the material contain but little magnesia, and a bitter taste if there be much of the latter present. Thus the drainage of a basalt region should furnish magnesian, and of a trachyte country saline waters. The silica, alumina, lime and iron are thus left to form the sedimentary rocks. The iron plays its part chiefly as a component of the clays and a cementing material for the sandstones, to be afterward leached out and accumulated in local deposits as bog iron, which by the changes of time becomes the source of other iron deposits of various kinds. The lime, being less soluble than the alkalies, is slowly leached out of some of the rocks, especially by water containing car- bonic acid, and redeposited on exposure to the air as a sediment by the springs which have dissolved it, or is carried to the ocean to furnish material for the coralline structures or the shells of its multitudinous life. The guartz and clay, the chief constituents left, fur- nish the bulk of the sedimentary material, which, with the addition of waterworn fragments of undecomposed rock naturally resolves the deposits into two series, to the first of which belong the conglomerates, gravels and sands, and to the second the muds and clays (derived chiefly from the alumina), shales and slates. All material washed into a stream by the rainfall on the adjacent hills, and falling therein by the under- mining action of the current on the banks, becomes a source of sedimentary deposits. If the fragments are too large to be moved by the current, they remain in the stream bed until gradually worn away by the attri- tion of smaller rocks and sand over them ; if smaller and movable, they are only carried along to the first dead water, whether it be a lake or the ocean, and thero 60 PROSPECTING AND VALUING MINES. deposited, and this deposition involves a sorting of the material. The larger and heavier pieces will be deposited first as coarse gravel, then finer gravel, then sand, and the finest sediment being carried the fur- thest will be laid down as mud or silt, unless the lake be so small and the current of the stream so swift that it is swept into the outlet beyond, leaving only a deposit of sand and gravel. It will thus be seen that the same material may appear as gravel at one place, sand at another, and mud at another. But large streams usually carry only the finer sediments when they reach comparatively level country, having left the larger particles at the foot of the mountain slopes, and as in the case of the Amazon they may spread this over a sea bottom hundreds of square miles in extent. A similar process is carried on at the sea beaches where the reflux of the tide may carry the finer material sea- ward, leaving the coarser at the foot of the bluffs. While stratification usually occurs horizontally, it is not necessarily so, as in the case of mountain streams the coarse gravel would accumulate the most rapidly, forming a sloping bank, on which the layers deposited in successive flood times would take the same inclination. So, in like manner, the ashes ejected from volcanic cones, falling on the sloping sides of the same, would accumulate in layer after layer, presenting all the appearance of deposits made in water, but retaining the slopes of the flanks of the cone. Conglomerates are largely formed on sea beaches by the rolling of the rocks washed out of the shore bluffs into rounded fragments, which will naturally be of various kinds of rock, according to the material of the hills which are being worn away. Deposits formed by river action are apt, from the circumstances under which they are formed, to be much more limited in extent than those made along shore lines. They con- sist of rounded pieces of rock of various kinds ROCK-FORMlAls MINERALS AND ROCKS. 61 cemented together either with hardened clay or silica, and sometimes with iron oxides derived from percolat- ing waters or the black sand. They may be fairly fine if made of gravel, or excessively coarse, and, if made up chiefly of one rock, may be known by the name of that if it is specially desired to distinguish and separate them, as quartz-conglomerate, or trachyte-conglomerate such as is found in connection with the lavas of the California gold-gravel channels. Some of the schists contain bowlders, leading to the conclusion that they are, in this case, merely altered or metamorphic conglomerates; and in other cases the cementing process is so perfect and the consolidation of the mass so complete that the pebbles will break in two on a general line of fracture, without becoming removed from the mass. Cuttings through conglom- erate beds stand with nearly vertical walls. Sandstones consist essentially of sand cemented to- gether with iron, each grain being coated with a thin film of iron oxide, which imparts the general color to the mass, as in the red sandstones. The grains of sand when cleaned of the coating may be either tinted or colorless. Mica forms a common addition to many sandstones, as well as lime and clay, when they may be distinguished as mica-sandstone, etc. The lime and clay are not readily discernible to the unaided eye. Flagstones are only sandstones which split easily into thin slabs, suitable for sidewalks. Buhrstones are sandstones so thoroughly cemented that they are very hard and rough enough to furnish the grinding surface required in millstones. "Freestone" is some- times a sandstone which cuts freely in any direction, either with the stratification or across it, but hardens on exposure to the air. The term is however some- times applied to limestones and other rocks which present the same characteristics. Quartzite is a sandstone which has been subjected to the action of heated waters, which have aggregated 62 PROSPECTING AND VALUING MINES. the grains of sand together with a silicious cement, probably derived from a partial solution of the grains of sand themselves, until the rock has lost its granular structure, and to a large extent resembles massive quartz. It is a common rock in mining regions, and occurs with other metamorphic rocks, but also in situ- ations where the associated strata have undergone no change. Clays are formed out of the alumina in the feldspar and other minerals, silica excepted, of the eruptive or volcanic rocks, and are the finest of the sediment car- ried in suspension by water, varying in color and com- position according to the rock to which they owe their origin, and the particular stage in the journey of the stream at which they were deposited. They may be exceedingly pure, in which case they are called "fat" in the language of the brickmaker and potter, and from this range downward to a clay loam, in which there may be a very large excess of impurities, of which iron forms a large part. The richer clays require the addition of sand to make good brick, but possess the advantage of a more uniform composition, which enables the manufacturer to regulate the addi- tion of sand to a nicety and thus produce an article of uniform quality; the poorer kinds make only the most inferior grades. Fireclay. A good fireclay has a composition of silica 73.82%, alumina 15.88%, oxide of iron 2.95%, water 6.45, with traces only of lime, sulphur, mag- nesia, soda and potash, which is very nearly the chemical composition of granite, with the lime, potash, soda, and magnesia eliminated, so that such clays could easily be formed by the decomposition of that rock. Fireclay is largely associated with coal seams, the clay floor retaining the waters which made the tangled swamps in which many coal beds were prob- ably formed. Kaolin or porcelain clay is derived from the decom- ROCK-FORMING MINERALS AND ROCKS. 63 position of the feldspars of the granitic rocks and por- phyries, and is essentially a compound of the oxides of silicon and aluminum mixed with water, the composi- tion when pure being silica 46.3%, alumina 39.8%, water 13.9%. Impurities are frequently present, the principal one being iron derived from the other min- erals present in the rock from which it was formed. When pure it is white, ranging through yellowish to brownish red, when much iron is present, say 5% or upward. The preparation of the clay by grinding, washing and settling is a slow and tedious process. Shales are only hardened clays which have been de- posited from time to time in thin sheets, so that the resulting mass splits readily into thin layers along the lines of deposit; but while they all retain this common character, they vary greatly in composition, and may be distinguished from each other by the names of the minerals which may give a special appearance to the rock, as mica-shale, hornblende-shale, silicious shale (when sandy) or simply clay-shale. In color they vary as much as in composition, from pale gray to black ; in the latter case they are usualb r colored by small scales of graphite black-lead or plumbago derived from the carbon of the organic matter washed down with the clay sediment and buried with it. This organic matter may be so abundant that the shales may be called bituminous or oil-shales. Slates. For all this series of rocks the term slate is also very generally used, as clay-slate, mica-slate, etc. ; but, strictly speaking, the term slate is applied only to those rocks which have lost their shaly char- acter by end pressure cm the strata, and now split on the lines of cleavage, as previously defined, such as roof- ing slate (pi. 12, fig. 4). In these latter rocks the particles have rearranged themselves at right angles to the line of pressure. This effect has been repeatedly produced exprimentally, and the student must early relinquish the common idea of the absolute rigidity of 64 PROSPECTING AND VALUING MINES. rocks. As a matter of fact, they are plastic or may be molded to an extraordinary degree, many of the shales and slates having been folded and wrinkled like sheets of paper, and this not only on a grand scale, but down to the most minute plications. Samples of this fold- ing are shown in pi. 12, fig. 8, where the folding element has been the intrusion of the dike d; and in pi. 4, fig. 6, where the cause has been general lateral pressure, crowding the rocks into a smaller amount of space horizontally. Not only can cold lead under a suffi- cient pressure be squeezed as a jet through an aperture suitably provided, but cold iron can also be pressed so as to penetrate into the angles of suitable molds. This facility with which rocks can be modified in their structure, and bent and folded, has an important in- fluence on the filling of veins, as intense heat is developed in the process, and this, in the presence of water, will decompose and rearrange all the compo- nents of the rock, dissolving some which are replaced by new combinations and producing metamorphism. SECONDARY GROUP, METAMORPHIC SERIES. All the shales and slates may be thus converted into schists, previously described. As in the case of the shales, each variety may be distinguished by the predominat- ing or characteristic mineral, as mica-schist, which gradually shades off into gneiss, which is a rock hav- ing a composition exactly like granite, but without the uniform crystalline character of the latter, or the foliated structure of the schists. In gneiss there is a tendency for all the mica to be laid in horizontal or more strictly speaking parallel lines, while the quartz may occur in pure bands, and there is a tendency of the mass when viewed on the large scale to look like a coarsely stratified rock. From this characteristic ap- pearance there may be a gradual change until it is hard to say whether the rock should be called gneiss or granite, leading us to the conclusion that many so- called granites are only the last stage of the metamor- ROCK-FORMING MINERALS AND ROCKS. 65 phisrn of an original sandy bed of clay containing mica, such as are common everywhere. When hornblende is the chief mineral, we have hornblende-schist, a tough, dark greenish rock, which shales off into a rock so essentially composed of horn- blende that it loses the schistose character and be- comes what is called hornblende rock. When the shading off is in the direction of a more crystalline structure, the gradations may be toward a hornblende- gneiss, and from that to syenite, just as the mica schists grade into granites. It will, of course, be understood that these changes are not to be seen in small speci- mens, but only in the large area of a mountain range. When the metamorphism has proceeded so far that the micas have been decomposed, so as to liberate the magnesia by the absorption of water, we have a series of rocks all of which are characterized by a smooth, slippery, greasy feel to the touch, commencing with talcose schists, of a greenish or yellowish tint; inclin- ing to reddish from the decomposition of the minerals containing iron. On further change we may have asbestos, forming in the seams and joints of the rock, or the whole mass may be converted into soapstone, which is a compact whitish or greenish rock, without pronounced crystalline structure, easily cut by the knife or turned in a lathe. From its infusibility and the facilit3 r with winch it can be cut into suitable blocks, soapstone forms an excellent lining for fur- naces which are subjected to intense heat. Chlorite-schists are similar in composition to talcose schists, but the talc is replaced by an apple- green mineral called chlorite, which not infrequently occurs along with quartz in mineral veins, as on the mother loile in California and elsewhere. This series of rock 3 may be thus summed up, on two lines of progressive alteration, according to the start- ing point: (1) Sands, sandstones, quartzite; (2) muds, clays, shales, schists, gneiss, syenite or granite. 66 PROSPECTING AND VALUING MINES. SECONDARY GROUP, FRAGMENTAL SERIES. Besides the rocks previousl3 T described, all of which show evidence of deposition in water and something like a regular order, there are still a few which cannot strictly be classed with them. These are either volcanic or glacial. Volcanic Products. Yolcanic outbursts are often accompanied by the discharge of enormous quantities of dry dust and stones, some of which are rounded and others angular, or the dust may be an impalpable powder. Some of these may have been deposited under water, when they naturally have a distinct strat- ification; while in those laid down in the open air this structure may not be so well defined, though the alternating character of the material ejected may have formed apparently stratified layers on the sides of quite steep mountain cones. The discharges may consist entirely of lava fragments, or may include pieces of all the rocks traversed by the volcanic vent, and in many cases they have been cemented together by a lava paste. The various conditions in which they are found suggest appropriate names, as volcanic con- glomerate, where the pebbles and bowlders are rounded; volcanic breccia, where these are angu- lar; volcanic agglomerate, where there is a mixture of the two foregoing, usually without any distinct strati- fication. The finer materials are called tufas or tuffs and as a rule are distinctly stratified ; and while of volcanic origin may contain organic remains or fos- sils, equally with ordinary water-formed sediments. The term lapilli is applied to the coarser portion of the volcanic dust, so largely ejected prior to the ap- pearance of lava at many volcanic vents, to distinguish it from the finer volcanic ash, which may be a powder so fine that it can be carried hundreds of miles by the wind before finding a final restin * place. This finest ash forms a large part of the sediment brought up from the floor of the deep sea, where it gathers as slowly and silently as dust in a deserted room. ROCK-FORMING MINERALS AND ROCKS. 67 Glacial Products. While all the material dis- charged by glaciers into running streams is undistin- guishable from other sedimentary deposits, those dropped by melting ice present only faint traces of sedimentation or none at all. Where floating ice is dropping its load of earth, sand, gravel, rounded bowlders and angular fragments, on the top of strata which are forming under the surface of lakes or shal- low seas, we may find immense bowlders or bunches of gravel irregularly mixed with such deposits, which, while they betray the condition of the climate at the period of their formation, do not justify any special name to such accumulations of sediment. But where the glacial deposits are laid down by ice in deep waters, where the deposit of river or ocean sediment is forming very slowly, we shall have an irregular ac- cumulation of material, without the regular stratifica- tion of river deposits, showing only what may result from the more rapid descent of the largest pieces, which, if they fell on a surface already smoothed by the more slowly descending finer sediment, would pre- sent faint traces of sedimentation, but the lines would not be traceable for more than comparatively short distances, the successive deposits fading out laterally and overlapping each other. Such also are the de- posits of bowlder clay which have also been formed by the grinding action of an ice sheet. There is nothing to prevent such deposits carrying ore, except the irreg- ularity in their composition on account of the wide area from which they may be drawn, and the uncertain distribution of the valuable metals in the earlier rocks. GEOLOGIC SUCCESSION OF EVENTS. *It is scarcely with- in the scope of the present volume to enter into a description of the geological succession of the rocks, as it would require a volume by itself and be of little practical value to the miner, except as regards coal and iron, the character of which is largely influenced by their geologic age, owing to the changes which 68 PROSPECTING AND VALUING MINES. have taken place in their composition with the lapse of time under the influence of heat and pressure. The accompanying table gives the outline scheme adopted by the U. 8. Geological Survey. The pro- gression is from the bottom upward, the order being as shown in the stratified rocks now accessible, though the whole series does not appear in any single locality. Below the Archaean is the granite foundation. "Era" and "period" relate to time; "system'' and "group/ 9 to the rocks. Subdivisions of periods and groups are called "epochs" and "formations" (according to time and rocks respectively). The names for these smaller divisions vary in different localities, and authors differ in classifying and naming them, so that a more com- plete presentation here would only be confusing. ORDER OF SUCCESSION OF GEOLOGIC TIME AND ROCK FORMA- TION. Era or System, Period or Group. Era of Man ............................ Quaternary. I Pliocene. Cenozoic or Tertiary .................. < Miocene. ( Eocene. ( Cretaceous. Mesozoic .............................. -< Jurassic. ( Triassic. f Permian. I Carboniferous. Palaeozoic .............................. -{ Devonian. I Silurian. [ Cambrian. [See also the arrangement proposed by LeConte and Dana, pp. 332, 323.] CHAPTER IV. PHYSICAL CHARACTER OF MINERAL DEPOSITS. MINERAL deposits may be roughly classed under three heads : Beds, veins and masses. These divis- ions correspond to differences in form, and, in part, to differences in origin. BEDS. A large proportion of the rocks met with consists of substances arranged in distinct stratified layers. If any of these layers consists of a useful mineral, or contains enough to make it valuable, it is said to be a deposit in the form of a "bed," "seam," or "stratum," sometimes spoken of as a "bedded vein" or "blanket vein. " The most important of all bedded or stratified deposits is coal; but in addition there are beds of iron ore, copper-bearing shales or slates, lead- bearing sandstones, silver-bearing sandstones, gold, tin and platinum-bearing gravels, as well as beds of rock salt, clays, slates, limestones, gypsum, oil shales, etc. The characteristic feature of a bed is that it is a member of a series of stratified rocks, and as such was laid down or formed after the rocks on which it rests, and before those which lie on its top. This peculiarity at once distinguishes a bed from a true vein. Eoof and Floor. The layer above it is called the "roof "of the deposit and the onebeiowit the "floor," when it remains horizontal or nearly so, but when highly inclined the terms "hanging wall" and "foot- wall," applied to true veins, are equally applicable to beds, but less expressive. Thickness. This is the distance from the roof to 70 PROSPECTING AND VALUING MINES. the floor at right angles to the inclination of the floor, being the shortest distance between the roof and floor, and this may be very much less than the length of a crosscut run through the deposit on a horizontal line, the two becoming nearer in length as the bed ap- proaches more and more to the vertical ; in the latter case they would be equal. Dip is the inclination of the floor from a hori- zontal plane, and may be spoken of either in degrees of a circle, as for example ten degrees (10); or ex- pressed in feet, as 1 in 10, 1 in 20, etc. Other equiva- lent terms are "slope," "pitch" "underlie" and "inclination." Dip, of course, is due to the disturb- ance of the deposit by elevation or depression, causing tilting or bending, since its formation (a horizontal layer having no dip); but as such disturbance has been almost universal, nearly all bedded deposits have more or less dip, at the present day. Sometimes the beds may be nearly horizontal, as in Staffordshire, England ; or raised to an angle of 50 as in the Cumber- land coal series in the Skagit Valley, Wash. (pi. 2, fig. 10); sometimes they may be vertical or even folded over as in pi. 4, fig. 6, a structure which is found in the Appalachian mountains, and in some of the Franco- Belgian coal fields, where a vertical shaft passes six times through the same bed, because the folding has been so complicated. Strike. The strike or course of the bed is the di- rection of a horizontal line drawn along the floor of the deposit, such as the bottom of a tunnel following the mineral, without grade. This direction will clearly be at right angles to the dip of the bed, and will consequently vary as the dip varies; so that, if it is desirable to run a tunnel on a deposit in a perfectly straight line, it must have a course or direction as nearly as possible at right angles to the general dip, instead of to the dip at any particular locality. But this is not always possible. PHYSICAL CHARACTER OF DEPOSITS. 71 From the above it will be clearly seen, by reference to pi. 13, figs. 10, 11, 12, 13, that while in fig. 10 the strike would be east, in fig. 11 it would vary from northeast to east and thence to southeast; in fig. 12 it would be north, going round by east until it was south; while in fig. 13 it would turn to all points of the compass in succession and indicate a saucer-shaped basin. From what has been previously said it will be obvious that even when the bed may be covered on the surface its position, if it exists beyond the point of discovery, should be traceable by the rocks with which it is associated ; but a search in this manner should be governed by the rock which forms the roof, as this must lie comformably above it, while it is pos- sible that the deposit may lie on the upturned edges of a great variety of rocks as at E, pi. 2, fig. 1. The thickness of workable beds varies within very wide limits according to their richness in some special mineral or its scarcity. Some workable beds of coal are only 1 ft. thick and range up to as much as 60 ft. or over in exceptional cases. The copper-bearing shales of Mansfeld are only from 10 to 20 in. thick, while the lead-bearing sandstones at Mechernich are no less than 85 ft., and some beds of slate, limestone and salt greatly exceed these dimensions. But what- ever the thickness may be at any particular point, it does not follow that this will be maintained over the entire area of the deposit. Sometimes this may be the case over a very extensive area, but there must neces- sarily be a boundary to the deposit in all directions, and toward these limits it may dwindle away to a feather edge, with the probability of the greatest thickness being near the central portions of the orig- inal deposit (not necessarily that part left to our inspec- tion). Toward these edges, as in the case of coal and iron deposits, the bed may contain many impurities and become valueless; or in the case of slates and limestones a gradual change may take place into 72 PROSPECTING AND VALUING MINES. another kind of rock, such as clay-shales into sand- stones and these into conglomerates. PL 2, fig. 1, D, shows a bed of coal, as originally laid down, thinning out in all directions. It may consist of a uniform mass, with impure edgings, or it may be divided into several layers by thin sheets of clay or waste matter, called "partings," in which case it often happens that the character of the coal above a parting is different from that below in important particulars, and should be mined separately. Partings are not necessarily a detriment to a deposit, as they frequently facilitate mining. Outcrop. It is not always easj' at first sight to dis- tinguish the outcrop of a bed from that of a true vein, but it will usually be found more continuous and more uniform in its composition. VEINS may be described as comparatively thin sheets traversing what are called " country rocks," which were formed earlier than the veins themselves; and occupy crevices formed by fracture of the inclosing rocks, or have been formed along the lines of junction of such rocks by changes in those adjacent,, It is this origin at a later date than that of the rock formation which constitutes the essential difference between a vein and a bed. Dikes. The above description includes all veins of porphyry or other intruded rocks, such as granite or basalt, as well as those containing the useful or pre- cious minerals. Veins filled with porphyry or similar rocks of whatever kind are usually called "dikes." True Veins. The term "vein" is more properly restricted to those which are more or less filled with useful minerals, whether in workable quan- tities or otherwise. Building stone should be excluded from this definition, as many valuable varieties (besides those found in beds) are the product of dikes. In the United States the terms "vein," "lode," "lead" or "ledge" are used indiscriminately in different PHYSICAL CHARACTER OF DEPOSITS. 73 localities, but all have the same meaning, while in Australia and South Africa the term "reef" is often applied to mineral veins as well as to bedded deposits like gold-bearing conglomerates. For the purposes of the U. S. land offices the description of a lode as given by Justice Field in the celebrated case of the Eureka Cons. vs. the Richmond Co. is accepted, viz.: "We are of opinion, therefore, that the term [lode], as used iu the acts of Congress, is applicable to any zone or belt of mineralized rock,lying within boundaries clearly separating it from the neighboring rocks." This definition evidently covers both true veins and all bedded deposits. Miners often speak of coal and iron veins, but this is a misapplication of the term. When a bed lies on the upturned edges of much older rocks, as in pi. 2, fig. 1, E, it shows conclusively that before its deposition long periods of time had elapsed, in which the lower strata had been raised above the water, uplifted into new positions, worn down to a new surface and again de- pressed below the water level; and we can form some comparative idea of the relative ages of bedded veins by the thickness of the strata which have accumulated above them. In the case of true veins we can only judge of their age by knowing that they must be younger than the rocks in which they lie, and the comparative age of these is judged by the fossil remains found in them. Dip. Like beds, veins have dip, strike and walls. As a usual thing the dip of true veins is apt to be steeper than that of the majority of beds, though such a distinction is not absolutely necessary. The dip is measured from a horizontal line as in the case of beds, and is expresed in degrees. If the vein is vertical the dip is 90. In pi. 9, fig. 1, the veins A, B, C, and D, have respectively dips of 47, 68 and 86, while vein E is vertical (90). In some cases the dip may be so flat that when the vein is exposed by the wearing away 74 PROSPECTING AND VALUING MINES. of the hanging wall it may appear almost like a bed. Such cases are often termed "blanket-veins," but a very slight examination will show, in most cases, their true origin. Strike. Owing to their different origin, the strike of true veins is more likely to have a uniform direction than in beds, as the inclosing rocks have not usually been subjected to so much movement since the forma- tion of the fissure as has been suffered by the strata containing the beds; or, if movement has taken place, the weakness of the fissure has directed the motion into that plane and simply caused a reopening of the fissure, and not infrequently a refilling of it with a different class of mineral deposits. See pi. 6, fig. 6, where the thin slabs of rich gold ore B occur on each side of a large central core of poor or barren quartz A. The conclusion is frequently irresistible, taking into consideration the great amount of motion of the walls of the lode as shown by their shattered condition, that on a reopening of the fissure the contents of the lode were concentrated in the way shown, to the im- poverishment of the main body of quartz. Outcrop of Veins. The outcrop of a vein, sometimes called "croppings," is the portion of the vein exposed on the surface. It does not follow that the visible out- crop corresponds with the true strike of the lode. This can only occur when the vein is vertical, or out- crops in a level plain, when it would show a compara- tively straight line and the true course, whatever the dip mi^ht be. It is not often that such a case occurs, On the contrary we find the bulk of mineral veins in rough and broken mountain regions, and in these cases the tracing of the outcrop becomes a more difficult matter, especially when the vein crosses ravines or val- leys filled up with gravel or debris which hide its presence. All veins with a pronounced dip have a crooked or serpentine outcrop, and the fiatter the dip the more sinuous this outcrop will appear. By refer- PHYSICAL CHARACTER OF DEPOSITS. 75 ence to pi. 9, figs. 1, 3 and 5, these peculiarities will be easily understood. Their great importance be- comes apparent when making locations on a vein and in the legal aspect of these locations. Fig. 1 is a longitudinal section along the bed of a ravine, show- ing five veins A, B, C, D, E, and their outcrops ascend- ing the hill on the side furthest from the observer, as from g to s, h to r, k to p, I to o, and m to n. All the veins are supposed to run north and south. It is evi- dent that on the crest of the ridge the outcrop of the vein A, dipping east, will be west of its position in the gulch by the distance sa, while in the cases of the veins B, C, D, dipping west, the outcrops on the ridge will be east of the position of the veins in the bed of the gulch as shown at A, k and I by the distances br, cp, and do. It can also easily be seen that on de- scending the opposite side of the hill, the outcrop of A would swing back again up the ravine, while all the others would swing down, producing, if the outcrops were continuous, an appearance something like that in figs. 3 and 5. In fig. 3 we have details of the out- crop of two veins, B, B, and C, C, running north and south on the two sides of a ridge, and both dipping to the west; and in fig. 5 similar details of two veins A, A t and Z>, D, dipping east. The outcrops in fig. 3 are shown by the black lines A, A, and D, Z), and in fig. 5 by the similar lines B, B, and G, C. A little study of these figures will make the matter clear, without elaborate de- scription. All the peculiarities of the outcrop may be illustrated by taking a large smooth potato, and cutting it into halves lengthwise. Lay the two halves flat side down on the table side by side and we have two minia- ture hills with a ravine between them. Now if a cut be made across both hills inclining from right to left we shall have a vein in miniature, and if the pieces be drawn slightly apart so as to show the white of the inside in contrast with the brown skin, the pale line thus made visible will indicate the outcrop of the 76 PROSPECTING AND VALUING MINES. vein, and will be found similar to figs. 3 arid 5. By making the first cut flat and subsequent ones steeper the gradual approach of the outcrop to a straight line as the view becomes more and more vertical will be quickly apparent, until the vertical cut will represent the vein E in pi. 9, fig. 1. The outcrop may either be a very conspicuous object standing many feet above the surrounding sur- face or barely visible on the hillside; it may be merely outlined by a surface depression, or form a deep gorge, according to the relative hardness of the vein matter and the country rock, or the difference in the contents of the vein at different points in its length. Dikes, which have a nearly uniform composition throughout their length, often traverse a country for miles, standing up like ruined walls, as at the Devil's Slide in Utah, on the Union Pacific railway, and at other places which nearly every traveler can recall, but such uniformity very seldom exists in mineral veins. On the mother lode of California the barren portions are largely made up of threads and stringers, while the valuable portions consist of immense bodies of solid quartz, which have protected the present hills from wear and tear, while the ravines have been cut out alongside the lode (pi. 7, fig. 6) or through the barren portions at right angles, or nearlj* so, to the vein, as in pi. 9, fig. 7, where A, A, represent quartz bodies; B, the barren intermediate ground and c,c, the visible outcrops. This structure is continuous for many miles. In Mariposa county especially the heavy white quartz crops out from the crests of one hill after another, crossing their summits like the comb of a helmet, in a most conspicuous manner, with deep intermediate ravines. In these cases the ravines are due to the absence of ore in the outcrop, but in other cases the ravines are due to the presence of soft, friable, easily decomposed ore in the lodes, and form along the veins, in gorges of varying depth according to the PHYSICAL CHARACTER OF DEPOSITS. 77 degree of difference in hardness between the lode and its wall rocks. A good illustration of this structure is found in the Monte Cristo district on the west slope of the Cascade range in Washington, where the abrupt bluffs, forming the walls of an ancient glacier basin, are furrowed with deep, abrupt gorges, similar to pi. 9, fig. 6. The veins here cut across the slates with a dip of about 60, and having undergone extensive alteration, besides being mineralized with friable ores, are now softer than the metamorphic slates, so that as the vein wore away the overhanging wedge of rock B, broke off from time to time, leaving a steep slope to the footwall side of the ravine, and a nearly vertical bluff above the hanging wall, from which large frag- ments are annually detached by the action of frost and sunshine, widening the ravine, while at the same time the melting snows deepen its bed along the course of the vein. In such cases the foot of the bluffs is cov- ered with an immense " talus" or broken rock slope, consisting of angular frost-detached fragments broken from the cliff above, which have buried the outcrops in the lower portions of the valley, roughly indicating their position, however, by winrows of immense bowl- ders which have been detached, for want of support, from the overhanging wedge B } and have rolled down the slope without being more than partially broken up in the fall. In other cases the hardness of the vein matter and that of the inclosing rock may be so nicely balanced that they both wear down at about the same rate, and the croppings may be covered with earth, etc., or as the prospector says, "blind;" that is, hidden or hardly visible; or the vein may become blind because since the time of its formation new strata or volcanic over- flows have been laid down upon the containing rocks, as in pi. 15, figs. 13 and 14, which show such a case in longitudinal and cross section. In this case if ravines have cut down through the "cap-rock" the 78 PROSPECTING AND VALUING MINES. vein may be seen cropping on the side of the ravine as at A, fig. 13, being lost under the cap B, but reap- pearing at C on the other side of the hill. This cap may be either sedimentary or eruptive rock, or it may be the consolidated snow (nere) of a snowfield, both forms being seen in the Monte Cristo region; so that the importance of determining accu- rately the strike and dip of the vein, so as to recognize it on both sides of the mountain, becomes very appar- ent. But in whatever manner the outcrops may occur the same rule will generally hold good for quite an exten- sive district or group of veins, and a recognition of this fact may save the prospector many a weary mile of travel and hard climbing. If the vein has a very flat dip and is located on a more or less conical hill, it may even crop entirely round the summit of such a peak, as shown in pi. 7, figs. 10, 11, in which fig. 10 is a vertical section and fig. 11 a ground plan of the same. We have here a series of trap dikes with bedded quartz veins lying between granite and slate. The drawings represent the Yanderbilt mine near Silver Peak, Nevada, and show a similar structure to that of the Tyndall mine in Colorado. Spurs. It not infrequently happens that a vein pre- sents more than one outcrop, the main lode presenting itself at the surface with several minor lateral branches, as shown in the cross section of the Dol- coath mine, pi. 7, fig. 1. These are generally more numerous on the hanging wall side of the lode, and present in the greatest numbers when the dip of the vein is flat, as was the case in the Comstock lode, of which a general idea is presented in pi. 2, fig. 2. These ' 'spurs" may run nearly parallel to the main lode, and standing more vertically unite with it in depth, or they may run out into the general bedding of the rock, as shown in pi. 6, fig. 2, s y s,s. In the PHYSICAL CHARACTER OF DEPOSITS. 79 former case it is easy to understand how the cracks in which they are formed were made by the weight of the overhanging wedge breaking it across from time to time, or the sliding of the hanging wall on the foot- wall pulling it apart, a cause which might also give rise to the spurs which branch out into the bedding. Horses. In other cases, especially in very large veins, these spurs after leaving the vein may reunite with it in all directions, resulting in a mass of barren rock entirely surrounded by vein matter, to which the term "horse" is usually applied. These are fre- quently spoken of as masses of rock which have fallen into the fissure, but they have usually moved but a very slight distance, if at all, from their original posi- tion. Walls. When the vein is vertical the walls may be distinguished by the points of the compass, as the north, south, east or west wall, but when the vein has a slanting dip the lower wail is designated as the "foot wall" and the upper as the "hanging wall," as in pi. 7, fig. 7, where the granite forms the foot wall, and the slates the hanging wall of the quartz series B. In England the term "cheeks" is sometimes applied to the walls. Gouge. Not infrequently there occurs between the vein matter and the country rock a seam of clayey matter called "gouge" or "selvage," which may be of extreme thinness or reach a thickness of as much as 30 ft., as in the Potosi mine on the Cromstock lode. This is apparently the result of a grinding or crushing movement of the walls of the vein upon each other, under enormous pressure, and where a portion of the vein has been mixed with material from the walls the gouge is often rich enough in mineral to go to the reduction works. Mine clay may also result from chemical decomposition of the wall rocks. SlicJcensides. Where the motion has been consider- able, and the walls or vein are hard enough to resist 80 PROSPECTING AND VALUING MINES. the grinding action and reduction to clay, both the wall and the vein matter become marked with parallel lines or strice, called "slickensides, " or "slickens," which indicate the direction of the motion, and fre- quently the quartz or wall has taken a polish equal to anything which can be produced artificially. "Frozen" Veins. In other cases it may happen that there is only one well defined wall, the vein mat- ter being firmly attached to the other, and gradually fading out into the barren country rock, as shown in pi. 6, fig. 3, where (7, 6 y , may be slates or any other rock; A, a dike cutting the same, and B the ore vein with a well defined wall on the right hand but "frozen" to the dike on the left side. The condition of the walls is a matter of much interest to the miner. If the ore is frozen to its alls on both sides it is almost a positive indication of uncertainty of continu- ance in depth, but heavy clay seams or gouges are taken as favorable indications from the evidence they supply of a deep-seated fissure. Vein Matter. The material with which the vein is filled is known as the "gangue" or "matrix," usually by the former term. It is not necessarily quartz. It may be limespar (calcite, calcspar) fluorspar, barytes, or even the decomposed remains of a porphj^ry dike. The term matrix alludes to the filling being the mother of the ore. It does not follow that all this gangue carries ore, or that it is of uniform thickness through the entire length of the lode. The movement of the walls may have brought two swells opposite each other, as in pi. 6, fig. 2, at B and in pi. 2, fig. 9, and the vein is then said to "pinch" or "peter out;" or the ore maj 7 be confined to slabs on the walls, as in pi. 6, fig. 6, where B may represent ore and A the barren quartz gangue. Eig. 5, on the same plate, is an exaggerated representation of a condition fre- quently seen in the softer kinds of granite, where instead of the vein pinching completely, as in fig. 2, PHYSICAL CHARACTER OF DEPOSITS. 81 the motion since the vein was filled with quartz (black) has been able to reduce the portions of the wall rock between the swells B, B, to a condition of gouge or nearly so, and a new wall has been established as W y W. Ore Chutes. It may happen that all the gangue or matrix is charged with ore, but this is seldom the case. In the majority of cases there are wide and long barren spaces in the lode and the ore is concentrated into "chutes" (also spelled "shoots"), as shown in pi. 9, tig. 7, A, A. These may vary greatly in dimen- sions, being sometimes so short horizontally in pro- portion to their length that they are called "pipes." In addition to the dip, which they have in common with the vein, they have an inclination to the right or loft of a line drawn on the dip at right angles to the strike, which his called the "rake." For instance, looking down an incline on the vein, the ore may go off to the right or left of this incline, and this feature is usually common to all the veins in a district which have the same strike and dip, and the rake is usually the greatest in the flattest veins. In pi. 9, fig. 2 (a cross section) shows the dip of the vein, and fig. 4 (a longitudinal section) the rako of the ore chute C, which is estimated from the true dip line, in this case 37. MASSES. Under this head are included irregular deposits which cannot be classed as either beds or veins. Their forms are various, and sometimes they are mereb' indefinite impregnations in permeable ground, leached out from finely disseminated mineral in the surrounding country rocks. Some iron and manganese ore bodies, formed in troughs or cup- shaped depressions, are best described as "masses," as also are many segregated deposits of tin, copper, and silver ores. The most pronounced type is perhaps to be found in the large isolated bodies of lead and zinc ores in limestone. Small deposits, of whatever min- 82 R08PECTING AND VALUING MINES. eral, are called "pockets" or "bunches." The main characteristics of masses are irregularity and isolation ; but these do not prevent their being, in many instances, very valuable. If their shape is decided in any direc- tion, they may be said to have strike, dip, rake or pitch, roof and floor, or walls, etc. CHAPTER Vo ORIGIN OF VEINS. ALL veins of whatever kind, whether bearing valua- ble minerals or not, are the result of movements in the upper portions of the earth's crust, producing cracks or crevices, which have been subsequently enlarged and filled with some material different in its physical and chemical qualities and appearance from the rocks in which the fracture has taken place. These movements, which may be the result of earth- quakes, or the readjustment of the pressure caused by the thinning of one portion of the crust by denuda- tion and the thickening of another portion by the deposition upon it of all the material brought down from the mountains by the action of rivers, are inti- mately connected with the process of mountain build- ing, and consequently show themselves most striking!}* in mountain regions, in which also volcanic agencies have played a most important part. FISSURES AND FAULTS. Such fractures in the rocks, when they have been accompanied with more or less motion of one side of the mass upon the other, or of both on each other, are known as "faults'* or disloca- tions. They may show themselves only by a mass of broken material, or the break may be comparatively clean- cut, and may be very short, or extend for many miles, as in New Zealand, where one earthquake (1845) produced a fissure in the southern island which aver- aged 18 in. in width and was traceable for a distance 84 PROSPECTING AND VALUING MINES. of 60 miles parallel to the axes of the mountain chain, while the earthquake of 1855 gave rise to a fracture which could be traced along the base of a line of cliffs for a distance of about 90 miles. But whatever the cause and however long the fissure may be, it must terminate at each end somewhere, otherwise it would cut the world in two; and it is evi- dent that however great the elevation or depression of the bounding walls at any one point, there can be no such motion at its two extremities; and that the grinding action of the motion, which prepares the fis- sure for the formation of a mineral vein, must be nothing at either end, and greatest where the displace- ment of the walls has been most extensive. It does not, however, follow that all fissures will produce mineral veins, for there must be a combina- tion of circumstances to cause such depositions; but as these faults may have been, and often have been, formed subsequent to the formation of bedded de- posits such as those of coal, iron or gold-bearing gravels, it is therefore necessary to know something of the features which these faults present to enable us to again find a broken bed or vein when lost in the course of working. Throw. The simplest form of fissure is shown on pi. 3, fig. 4, AB, with the greatest motion at n,o; CD in the same figure (after Geikie) shows a fissure split- ting at the ends into minor branches, the amount of "throw" or displacement of the walls being given in figures, which indicate the greatest movement in the middle, as before explained ; while EF shows one in which the walls have been drawn apart at right angles, or nearly so, to the main fissure, forming "spurs." A similar structure is shown in pi. 6, fig. 2. In(7Z>, pi. 3, fig. 4, while the greatest total movement has been say 30 ft. it does not follow that all this movement was on one side of the fissure, for one side may have been raised and the other depressed in varying proportions. ORIGIN OF VEINS. 85 These figures are horizontal plans. PL 1, figs. 3, 4, 5 6, 7, show the simplest kind of fault in vertical cross section, if the break were an absolutely straight line, which, however, is not often, if ever, the case. Fig. 3 shows a fracture in a series of bedded rocks without any apparent displacement, although it is possible that there might have been such horizontally. Figs. 4 and 5 show a movement of either or both of the two walls on each other in the direction of the arrowheads; but there would be nothing in such a case, as the fracture is clean cut, to indicate the dij'ection in which the movement had taken place, whether the foot wall had been depressed as in fig. 5 or elevated as in fig. 4, or the reverse in the case of the hanging walls; but in fig. 6, 7, the movement is clearly shown by the bent and broken edges of the strata, to be an ordinary fault or depression of the hanging wall in fig. 6. Reverse Throw. Elevation of the hanging wall (or depression of the foot wall) is shown in pi. 1, fig. 7. Such a throw is also seen in pi. 11, fig. 5, from the gravel pit at Laporte, Cal. The direction of the throw is called the "hade. " Pockets Formed by Faulting. If a fault, instead of being a clean, straight cut, has a sinuous or wavy form, as in pi. 2, fig. 7, the result of motion of the walls in the direction of the arrowheads would be very different, producing the form shown in fig. 8, or a vein of very uniform width throughout, if the move- ment were a mere separation horizontally; whereas, if the movement had been in the direction of the arrows in fig. 9, the swells of one wall may have been brought against the swells of the other wall, resulting in a series of lens-shaped pockets, especially if the course or strike of the lode be also sinuous and it has suffered more or less longitudinal as well as vertical displace- ment. On sinking on the outcrop at a, fig. 9, the vein would be found widening rapidly, forming what the Mexicans call an "A" vein; while, if the surface had 86 PROSPECTING AND VALUING MINES. been worn away to the dotted line be, similar sinking would reveal a vein rapidly diminishing in width or a "V" vein. Very rapid widening of an ore body in this way is liable to be accompanied by an equally rapid contrac- tion, and vice versa. An easy method of getting a thorough understanding of this important phase of fissure structure is to tear a piece of paper in two halves along a wavy line such as is shown on pi. 2, fig. 7; when, by moving them apart in various directions upon a dark background, every phase of the question can be readily studied, particularly if in one instance the waves are made short and deep, and in another long and gentle. PL 6, fig. 5, is an exaggerated illus- tration of such structure, to show that when the ore (black) is lost at B the search for the next swell must be continued by following the crosshead or seam which cuts the ore body off (this being the original fissure line), and not by following the false wall W W, which has only been formed by the motion and pressure crushing the swells of the country rock AB into a shat- tered mass of vein matter; or, yet worse, by presum- ing that the course of the ore body is the general course of the vein, and following that direction into the country rock on one of the joints which originally determined the shape and position of the swells on the line of fracture. Gashes. When such fissures have been formed by pressure from below bulging the surface upward as in pi. 2, fig. 4, a simple gash may have been formed, which was later on filled with mineral matter from above or laterally; or by the action of surface waters, became, as we so often find, the line of a watercourse following an anticline e. A sagging in a syncline might conceivably give rise to the opposite effect, as in fig. 5. Step Faults. In other cases, the elevation has been so great, and the strain on the strata so enormous that ORIGIN OF VEINS. 87 when they did give way the central mass with the largest base exposed to the elevating force has been thrust furthest upward, while the masses on either side have settled down in gradually lessening steps until the movement fades out into undisturbed coun- try, producing a series of "step faults/' of which pi. 1, fig. 1 is an ideal and fig. 2 an actual illustration, the latter being taken from the reports of Prof. Em- mons on Leadville, Col., where the drop of 2,000 ft. at the Mosquito fault is reduced going westward to only 750 ft. at the Carbonate. Trough Faults. The faults shown in pi. 3, figs. 1, 2, 3, known as " trough faults/' are more compli- cated, and are best explained in the language of Mr. Jukes, who proposed the following satisfactory solu- tion of the problem: "Suppose the beds AA, BB, etc., fig. 2, to have been formerly in a state of tension, arising from the bulging tendency of an internal force, and one fissure, FE, to have been formed below, which on its course to the surface splits into two, ED and EC. If the elevatory force were then continued, the wedge-like piece of rock between these two fissures, being unsupported, as the rocks on each side sepa- rated, would settle down into the gap as in fig. 3. If the elevatory force were greater near the fissure than further from it, the single fissure below would have a tendency to gape upward, and swallow down the wedge, so that eventually this might settle down, and become fixed at a point much below its previous rela- tive position. Considerable friction and destruction of the rocks, so as to cut off the corners g, h, fig. 3, on either side, would probably take place along the sides of the fissures, and thus widen the gap, and allow the wedge-shaped piece to settle down still further. When the forces of elevation were withdrawn, the rocks would doubtless have a tendency to settle down again, but these newly included wedge-shaped and other masses would no longer fit into the old spaces, 88 PROSPECTING AND VALUING MINES. so that great compression and great lateral pressure might then take place/' PI. 4, fig. 5, (after Jukes) shows such a fault or wedge cutting into a bed of coal, which from the enormous pressure resulting from the resettlement of the strata "has been reduced to a paste of coal dust and very small coal." Very frequently the line of fault becomes the bed of a watercourse and in time a ravine. This may result not only from the weaker nature of the rock on this line (as evidenced by the faulting itself), but also from the tilting of strata along the fault plane. Such a fault-formed valley may or may not at present be occupied by a watercourse. PL 12, fig. 9, shows a canon following a fault in Death Valley, Cal. Every mountain region is full of faults, and they abound especially along the great ranges, where the movements have been so great as to bring to the sur- face, alongside of each other, rocks which in the order of succession are separated by many thousands of feet; and in these movements we have an explanation of the sudden change in the character of mineral deposits on opposite sides of lofty mountain chains which some- times seem inexplicable. But almost every vertical exposure of rock in such places as railroad cuttings, and not only of rock but of unsolidified beds of sand or gravel and clay, shows a multitude of minor fis- sures intersecting and displacing each other, some- times in the most complicated manner, but presenting evidence of the universality of the process which has opened the way for the circulation of underground waters, without which it would seem that the filling of a portion of the fissures could not have been accom- plished. There does not appear to have been any time in the earth's history since the first solidifying of the surface when such fracturing and movements have not been going on, and consequently we find veins of one age intersected and sometimes dislocated by others formed ORIGIN OF VEINS. 89 on fractures of later date, until in some cases there may result a very complicated condition, as shown in pi. 2, fig. 6, which a thorough knowledge of the theories of faulting alone can explain, and for want of which loss and disappointment may ensue from min- ing operations therein. It does not, however, follow that because one vein may be apparently faulted and thrown by another, such is always the case, as at the crossing of AA and (7(7, where the fissure A may have jumped along because the line of least resist- ance may have been different on the two sides of (7, which would make A younger than O\ but where the dragging of the rocks is present, as at the intersection of AA with BB, the presumption is strong in the absence of other evidence that AA has been faulted and thrown by BB. Clockworks. The complication arising from these sources may be so intricate that it becomes impossible to say which set of fissures is of most ancient date, and they may become so numerous and minute that individual mining becomes an impossibility, and the mass is extracted as a whole, if extracted at all, under the name of a "stock work. " Rocks vary so greatly in their hardness, texture, composition, brittleuess, and facility of splitting that they break in very different ways, and this peculiarity must inevitably exert an influence on the character of the fissures by which they may be traversed, and a knowledge of what may be expected in. each case is essential to a clear understanding of the methods to be employed in opening and working mineral veins to the best advantage. " True Fissure Veins." Anyone of the faults shown in pi. 1, which must evidently extend downward to an unknown depth, may under certain conditions form what is known as a "true fissure vein" (an old-time term for what was thought to be the best and most permanent type of a mineral deposit), which is simply 00 PROSPECTING AND VALUING MINES. a fissure, sometimes miles in length, coursing directly across the country in a more or less straight line, and cutting through the rocks indiscriminately, but vary- ing in width and character according to the rock in which it may occur both in length and depth, and tilled with mineral matter other than eruptive rocks. Strike Faults. A fault may cut the rock formations at right angles to their strike, or it may run more or less parallel with the strike, but cut the rocks on their dip, by being usually more nearly vertical than the strata penetrated, in which case the vein would be formed on a "strike fault/' and at the surface present many resemblances to what is known as a "contact vein." Effect of Country Bocks on Fissures. If the fissure is entirely in the same rock it may maintain a toler- ably uniform character for its entire length and depth, but if it cut rocks of various kinds it may pinch out almost entirely in those which are tough, expanding in those which fracture more easily, either from split- ting readily (as slates) or from extra brittleness (as certain quartzites). If it traverse a limestone forma- tion it may for a time completely Jose the character of a fissure vein with definite walls, in a comparatively short time after its formation, on account of the great facility with which lime is removed by the action of water, especially when containing carbonic acid, and the irregular cavernous structure thus caused. It therefore becomes an important question when ore is found in a certain rock to ascertain to what extent that rock is developed, and whether the associ- ated rocks are of such a character for hardness or soft- ness that a vein, as the miners say, can live in it* The writer has in mind an extensive region where the disregard of these general principles has led to the useless expenditure of large sums on veins which a very slight geological knowledge would have taught the miners could not be of permanent value, because, ORIGIN OF VEINS. 91 however rich the surface ores, they were contained in the fragments of a bed of schists overlying a tough solid syenite, in which the vein exposures were very narrow, and into which the veins found in the schists would inevitably pass in their lower portions. If the vein has been formed on a strike fault, there is a yet greater chance of irregularity from the ten- dency of the break at times to follow the bedding planes of the rocks, while at others it cuts through them, resulting in shattered masses which form "horses" or barren patches of country rock in the middle of the ore body ; or the fracturing may have been so extensive laterally that we have a mass of parallel threads and stringers, instead of a smaller but more compact deposit. CONTACT VEINS. From such veins as the latter the passage is easy to those formed on the contact of two bodies of rock of different kinds. Such contacts may be divided into four groups: (1) Contacts between sedimentary rocks such as slate and quartzite, quart- zite and limestone, or sandstone and conglomerate; (2) contacts between sedimentary and intrusive or igneous rocks, such as slate and granite, or limestone and porphyry; (3) contacts between two igneous rocks as porphyry and syenite; and (4) contacts on the walls of dikes which may traverse a series of either sedimentary or igneous rocks. When contact veins of the first two classes stand at a high angle or approach the vertical there is at first sight but little difference in their appearance from fissure veins, but as they alwa3 7 s maintain the same relation to the inclosing rocks they are apt to have a more uniform character both in structure and filling. It is plain also that they must partake of all the wavy irregularities of shape which have been imparted to the rocks in their upheaval, and if followed downward to a sufficient depth must eventually flatten out, as no beds of stratified rock can continue to descend toward 92 PROSPECTING AND VALUING MINES. the center of the earth indefinitely, from the very nature of their origin; still, the contact is usually of great extent, and there is no reason why the vein should not be so also. This feature becomes especially pronounced when the contact lies nearly horizontal or only slightly inclined, as at Leadville, because we are able to reach it with comparatively shallow shafts over large areas, the extent of w 7 hich in one direction represents the strike of a vertical lode, while the extent in the other is practically the same as the depth reached on the vertical lode only by deep sinking with all its limita- tions. In such horizontal contact deposits we do not look for horizontal motion, and have only to encounter the troubles arising from subsequent faulting, as in pi. 1, figs. 1 and 2, but in many cases of steeper contacts there are evidences of vertical motion, in which case we shall usually find the contact to be local and acci- dental ; the fissure being really a strike fault con- tinued to the surface on a contact plane which proved to be the line of greatest weakness, as in the case of the Comstock lode in Nevada, which strikes nearly parallel with the axis of the mountains on whose flanks it is located, and presents varying contacts in Virginia City, Gold Hill, and Silver City, but has been proved to descend into the syenite at Virginia City, below the level of the Sutro tunnel, the character of the lode changing at the same time as well as the composition of the ore. Thus evidence of motion in an apparently contact vein may be taken as prima facie proof that the contact is not continuous, and that the vein really belongs to the group of fissure veins, and will partake of all their peculiarities of structure and filling. When two sedimentary rocks are conformable, but have a more or less wavy surface of junction, a sliding movement of one upon the other will give rise to open- ings and pinches, just as in the case of secondary faults on warped planes in homogeneous rock, and an ORIGIN OF VEINS. 93 opportunity for the formation of a contact vein is presented, as in pi. 1, fig. 8. Such a vein might be regarded as either a contact deposit or a fissure vein, but is more naturally considered in the former class. As the rocks on the two sides of a contact are seldom of equal hardness the character of the vein will prob- abb r be governed by that which is most liable to decay, removal or fracturing. This is especially the case with slates and limestones, the former on account of the facility with which they split and crush; the latter because they are so easily dissolved. Compression Veins. No person with any experi- ence in the mountains can have failed to notice the folds and bends in slate rocks, from gentle waves to minute crumplings, which have been produced by forces pressing on the ends of the lines of stratifica- tion, until a structure similar to that shown in pi. 6, fig. 1, has been reached, a structure which can be easily imitated by squeezing the leaves of a book to- gether endwise, between the covers, held slightly apart. If such slates are on a line of contact, as at the Keystone mine, Amador County, Cal., and have been subjected to such pressure, many good mines have been the result; but where such action has taken place in the body of a large mass of slate, in the absence of an3 r special controlling element, such as a dike, great uncertainty will exist as to the extent of the movement, which, having full play in all direc- tions, may have simply resulted in a multitude of irregular minor foldings. In all such cases the whole vein does not consist of a continuous sheet of ore, although there may be such at the immediate contact, but of a series of lenticular masses, overlapping each other, which may occupy a belt several hundred feet in width, the broadest portion of one being generally opposite the thin end of another. It is obvious that such mines will require extensive cross-cutting to make certain that no ore body has been overlooked. 94 PROSPECTING AND VALUING MINES. Limestone Contacts. In a limestone contact, whether steep or flat, the actual line of contact which will form one wall of the lode may be comparatively smooth, while that in the limestone may be very irregular, depending somewhat on the solidity of the limestones or their varying degrees of solubility, and the destruction of the limestone by this means may be so complete that the ore body will apparently consist of a cemented conglomerate, the pebbles in which are only the insoluble cherty or flinty residue so abundant in chalk and silicious limestones. The remaining groups may be considered together, as while there may be cases of contact of two eruptive rocks without the presence of a dike, as on the Corn- stock, the majority of contact veins in purely eruptive rocks are alongside of or controlled by dikes cutting masses of some other variety, as in many Colorado mines. The essential feature of all lodes formed on the contact of dikes is that the latter have been squeezed from below into the fissures as they were formed, and that consequently their walls must extend downward to the source of the pasty rock with which they were filled, and that this source is, in depth, beyond our ability to explore. While such contact lodes thus present a general similarity to fissure veins in their length and depth, they possess one important feature not present in the latter that one wall of the fissure is always of the same composition, a fact which will tend to maintain a more uniform character in the filling, at least on one side of the vein. The wall away from the dike will, of course, be liable to changes as the rock of which it is formed varies, but such changes will be rather those incident to the influence of the heat of the injected dike, as the baking of clay shales into jaspery or flinty products, rather than variations in the shattering of the walls, as the forcing apart of the walls of the fissure and simultaneous filling with a plastic substance would prevent grinding of the faces ORIGIN OF VEINS. 95 of the fissure against each other, while such fragments of the walls as did fall off would be buried in the intruded mass, and carried by it upward on its course toward the surface if the rent extended that far. In such lodes we may find a sudden change in the prin- cipal mineral on passage from one rock to another, but ^ constant admixture of some other ingredient which owes its presence to that of the adjacent dike; Dr the ore on one wall may be of a totally different character from that on the other, as at the Key- stone mine, where, next to the so-called green- stone hanging wall, the quartz is massive, white and blocky, while that of the slate foot wall is banded with numerous parallel blackish lines of slate, making the "ribbon rock" of the miners; or, as on the Comstock, where the nearly vertical ore bodies in the porphyry, as they approach the much flatter syenite foot wall, carry an appreciably larger proportion of gold ; or, as at a mine in northern Washington, the ore on one wall may be distinctly a silver proposition, and on the other, only 15 ft. away, as decidedly a gold one. In all these cases of dike contacts, the point at which ore will form and the shape of the deposits will be governed by the same influences as in other con- tacts, whether the lode has been formed by the gradual shrinkage of the mass of the dike in cooling, or by substitution through the circulation of water along its bounding planes. Gash Veins. Shrinkage of sheets of lava may also produce veins which will not extend into the underly- ing granite or other rock, as at the Stonewall Jackson mine, Ariz. Such occurrences may be classed with the "gash veins." Segregated Veins. In other cases, like that shown in pi. 7, fig. 5, there may be neither a clean cut fissure nor a line of contact, nor a controlling dike, but a series of ore bodies arranged along a general line of shattering and without definite walls, the change in 96 PROSPECTING AND VALUING MINES. the rock becoming gradually less marked laterally until it fades out into the unaltered country rock. Such occurrences are known as "segregated veins, " by which term it is understood that the mineral has been concentrated by the action of water into the crevices of a shattered or sheeted belt of rocks from the sur- rounding rocks themselves. This "sheeting" is well seen in many mines in granite, where an apparently solid and smooth wall will scale off in slabs or sheets, after a short exposure to the air, making it almost im- possible to say where the true wall may be, and ren- dering a large opening necessary to secure a relatively small amount of ore. Many miners make the mistake of considering all the sheeted mass as a part of the vein, thus deceiving themselves with the hope that the ore body may ultimately be as wide as the sheeted por- tion. A little study will show the falsity of such a notion, as it is quite conceivable that the step faults shown in pi. 1, fig. 1, might be so numerous that the spaces between would not exceed the thickness of the slabs just spoken of. Most faults through rocks which do not break too easily into small fragments show this sheeted structure, as the result of the dragging of the sides at the moment of fracture. Where there has been much of this action we may look for more or less numerous veins parallel to the main lode of a district, which maj' carry more or less ore, but being only inci- dents accompanying the principal disruption are less likely to afford the conditions which will develop them into lodes of equal value. GENERAL CONCLUSIONS. It may therefore be set down as an axiom in mining that as a prior condition to the formation of mineral veins there must have been such fracturing of the rocks as to facilitate the circulation of underground waters vertically as well as horizon- tally, and that the nature of the fissures thus produced will be influenced by the varying hardness, brittleness or solubility of the rocks thus fractured, as well as by ORIGIN OF VEINS. 97 the direction in which the force may have been applied. The "filling" of the vein will depend on other condi- tions, but one may reasonably expect that the structure of veins in granite, for instance, will be similar in widely separated mining camps; and so of veins in tou:h limestone, or easily fissile slates, and other characteristic rocks; and we may take the generaliza- tion still further, and expect to find all the veins in any mining district, in the same rock and belonging to the same system, similar to each other in filling as well as structure. But it does not follow of necessity that all veins in any particular region are of the same age. On the contrary we frequently find several systems, each char- acterized by a general common strike and dip, show- ing that such regions have been the seat of several fis- sure-forming disturbances, which may have been of very widely varying force, and followed by fillings of a totally different character; but usually the most strongly developed system will either show a decided parallelism to the general direction of the mountain range, or else nearly at right angles thereto; and, while one system may be a good ore producer, another may be practically valueless. It thus early becomes necessary to identify their peculiarities and avoid loss. While absolute dislocation of the strata or rocks may have been necessary to produce the entire series of fissure veins, whether parallel to the strike of the rocks or more or less at right angles to it, simple fold- ing of the strata may have been sufficient to so far dis- place the lines of contact of two sedimentary rocks as to open the way for the formation of contact veins; or to so far rupture a belt of rocks without actual dis- placement as to permit the formation of segregated veins or deposits, or to rupture horizontal beds of limestone sufficiently to allow the percolation of water through them, with the consequent excavation of irregular chambers. 98 PROSPECTING AND VALUING M1NEH. These changes are common to all mountain regions, and are not unknown even in comparatively level countries, but they have not resulted in the formation of mineral veins in all localities. There are extensive mountains areas almost entirely destitute of valuable mineral deposits; and therefore, while the preliminary fracturing of a country is absolutely essential to the formation of mineral veins, their subsequent filling with valuable contents must be explained by the operation of agencies which were local in their action, and at the most very indirectly connected with the agencies which formed the original fissures. The frac- turing of the rocks simply made the formation of the veins possible. The formation of a crevice did not necessarily involve the formation of a vein, but only governed the physical aspect of such a vein when formed. CHAPTER VI. FILLING OF MINERAL VEINS. Igneous Theory not Tenable. It is a popular idea that all mineral veins have been filled from below by the material being forced into them while in a molten condition. This would involve intense heat. While there can be no question that the porphyritic and basaltic dikes have been filled in this manner, a multi- tude of facts compel us to look for some other explana- tion for the majority of metalliferous veins. That the intrusion of dikes has been accompanied with heat is abundantly proved by the changes which have been effected in the rocks through which they pass, or into and between which they have been squeezed as sheets. When cutting through coal beds or penetrating them, as in pi. 5, fig. 6 (after Jukes), which covers a length of nearly 1,000 ft., the coal has been deprived of its volatile matter and becomes what is called " blind coal/' or is even reduced to a small quantity of black soot. Sandstones become fused into a glassy quartzite ; slates are hardened into a flinty sub- stance with change of color, while other rocks have become porphyritic, as alongside the great trachytic dike which cuts across Onion Valley in Plumas Coun- ty, Cal. This dike has a width of about 30 ft. and stands up as a wall on the hillside to a height of 90 ft. in places, and is apparently connected with surface sheets which overflowed from it. The country rock is a blackish green slate, but close to the dike it has been so altered as to look like a porphyry, being spotted 100 PROSPECTING AND VALUING MINES. with white feldspar crystals, which gradually become less conspicuous as the vicinity of the dike is left, until they fade out entirely in the plain-colored, unaltered general country rock. The same lava flow contains large fragments of the country rock which have been torn from the sides of the fissure during its formation, and altered in exactly the same way, just as we con- vert clay into brick by the action of heat. From these well established facts we would be justified in looking for similar changes in the walls of mineral veins, if they have been produced in the same way. We do find changes in the walls, it is true, produced by the action of heat, but they are such as result from the action of hot water and steam, and not of molten mat- ter. The latter when once injected will gradually cool off, and when once cold will produce no further change, while the hot water may continue to circulate for ages, so long as the source of heat remains un- changed, and produce changes much more extensive and more widely disseminated than the action of injected lavas. A few illustrations may render the discussion of this question more intelligible, and lead naturally to the important influence which rocks have on the nature of the vein material. It is well known that if we melt copper and silver together we produce an alloy in which the silver is indis- tinguishable except by assay or analysis, yet in the Lake Superior copper mines we find blotches of white silver in the heart of solid masses of native copper or crystallized on the surface of the copper, showing that in the latter case plainly, and in the former by infer- ence, copper and silver were deposited in the vein alternately, some of the silver at least after the forma- tion of the copper had ceased. At the Head Center mine, Tombstone, Ariz., crystals of gold are found planted on the surface of horn silver (chloride of silver) ; yet when melted together gold FILLING OF MINERAL VEINS. ' 101 and silver form an alloy with the kreatest facility, and the affinity of the metals for each other is so great that native gold always contains more or less silver. At the Alston Moor lead mines in England, where galena in a matrix or gangue of fluorspar is worked, lead crystals (galena) are bedded in fluorspar, with lime crystals (calcite) planted on the lead crystals, and crystals of "blackjack" (zincblende) on the lime crystals four minerals superimposed on each other, one at least of them (zincblende) volatile at a low temperature and another (lime) practically infusible. In the Sierra Nevada mine, Virginia City, Nev. , a seam of broken rock and clay, which has been made since the formation of the vein, is filled with minute crystals of red oxide of copper, formed by the coppery waters which filter through it from the higher levels. In the upper part of the wash of Furnace creek, on the eastern side of Death Valley, Cal., is a beautifully regular vein of fibrous limestone (satin spar) cutting nearly vertically through beds of coarse conglomerate, which show no signs of alteration (pi. 7, fig. 8). Fig. 9, same plate, shows quartz veins in the same neigh- borhood and similarly located. In the mines at Batopilas, Mexico, native silver occurs in veins of calcspar, which have an extraordi- nary persistence, frequently dwindling down to a mere seam, often less than 1 in. wide for long distances, and then opening out to a width of several feet. In places probably 90% of the ore is crystallized native silver, a large proportion of the remainder being crystallized ruby silver (arsenical) and crystallized black sulphide of silver, the latter often in branching flakes like moss formed in the joints of the rock alongside the veins. Near Yankee Hill, Butfce County, Cal., beautiful specimens of crystallized gold are found in the joints of the porphyries, usually in thin flakes, taking the shape of combs, fern fronds, etc. In this case there is no indication of veins or vein matter. 102 PROSPECTING AND VALUING MINES. At West Point, CalaveSras Co'unty, Gal., gold occurs in the solid granite. At Drytown, Araador County, Cal., gold occurs in limestone; and in Mariposa County, near Coulterville, both in the black clay slates and serpentines. At Fiddletown, in Eldorado County, gold is found in the iron pyrites which abound in the slates. The crystals are often of considerable size, chiefly cubes, and the gold can be seen projecting from the smooth faces of the crystals. It would be possible to extend the list of similar cases of crystallization indefinitely, but it is not neces- sary to more than call attention to the fact that in many cases, if not in all, these crystals are formed in cavities, many of them of such size as to be called caves or caverns, which are not characteristic of any of the dikes which we know to be the result of injec- tion from below. Good illustrations of this formation of crystals in closed cavities may be seen in the hollow balls filled with quartz crystals, called "geodes. " The miners call the smaller cavities found in veins "vugs. " Metals also occur in gash veins which must have been filled from the surrounding rocks, having no con- nection with the interior of the earth. Galena occurs in irregular deposits in limestone, where there is no evidence of vein structure. Chrome iron occurs in isolated masses in blackish- green hornblende schists; while platinum, iridinm, osmium, etc., occur chiefly as grains in sand or gravel deposits, which have probably been derived from the decay of rock strata, and not from veins, as their occurrence in veins is unknown. In the case of the "compression veins" in slates, as at Amador and Sutter Creek, Cal., pi. 6, fig. 1, the ore bodies, carrying gold, are often completely sur- rounded with slates identically the same as the black clay slates to the westward of the vein, which show 110 trace of alteration by heat either as applied by molten lava or hot water, although they have been subjected FILLING OF MINERAL VEINS. 103 to immense pressure and have been folded in every direction. In Cornwall the remarkable case occurs of a vein producing copper for many hundred feet in depth, while encased in slates (called "killas"), but chang- ing to tin when it passes into the underlying granite, as shown in pi. 8 and pi. 7, fig. 1, which represent a longitudinal section and a cross section of the Dol- coath mine. Again, we have those peculiar veins in which the minerals are arranged in bands parallel to the walls, as in pi. 7, fig. 4. This case is similar to those in which crystals of different minerals have been deposited on the top of each other in succession. In pi. 7, fig. 5., we have a case in which a band of rock has been altered, and contains more or less parallel ore bodies (shown in black), with numerous threads and stringers connecting them, the whole "stockwork" fading out into the inclosing rock with- out any positive definition or walls. Many other cases of interest might be cited, but these are sufficient to show the difficulties which surround the theory of igneous filling of mineral veins from below by injection in the form of molten or pasty matter. In the case of the limestone deposits there is no con- nection by well defined fissures wich the interior of the earth, through which the filling could have taken place; and in the case of the Batopilas mines it is in- conceivable that a mineral so infusible as limespar could have been injected into fissures, frequently less than an inch in width; while if we admit the possi- bility of the lime being fused, the heat would have been so intense that the adjacent rocks would have been fused into lava, and the minerals found in the injected material would have been volatilized and entirely eliminated, unless retained by condensation in the cooler surface rooks, in which case the ores would be found only near the surface and in the coun- 104 PROSPECTING AND VALUING MINES. try rock as well as in the lode, and the latter would be barren or unproductive in depth, which from actual exploration we know is not the case. That heat does operate in this way we know from the quicksilver mines of Lake County, Cal., where the surface rocks are filled with minute globules of mercury, which have been brought up from below by the action of hot springs and steam, and condensed near the surface, where the temperature fell below the volatilizing point of the mercury. Similar difficulties meet us in the case of the lime vein on Furnace Creek, and indeed in all cases where minerals occur intimately associated with limestone, either in the body of the rock itself, or in the crevices, or where it becomes the gangue accompanying the ore. The occurrence of gold in porphyry, slate, lime, granite and serpentine, outside of veins, is also inex- plicable on the theory of upward injection ; as also the presence of minerals in gash veins and the slates Of the mother lode in California. The same appears patent of all those cases where minerals are found which readily form alloys and have a similar melting point, in close contact, yet each re- taining its individual character; as well as in all cases of superimposed crystals lining cavities or vugs in the vein, especially where the cavities are of such dimen- sions as to become worthy of the name of caves. That crystals do form in dikes or veins of igneous (or rather of plutonic) origin is not denied; but they form a compact mass, the various minerals crowding each other to distortion, and mixed in tolerably uni- form proportions, as in granite and the porphyries, in which cavities are almost unknown; while such crystals as they do yield outside of the mass are found in crevices formed at a later date than the origin of the rock. We have still the case of the Cornish veins, which is only a type of many others, where the imagination can FILL I NO OF MINERAL VEINS. 105 hardly realize how a vein can be filled from below, during the same operation, with copper in its upper portion and tin in its lower, and why the change in the character of the injected material should have taken place just at the junction of the two rocks which were traversed by the fissure. In such cases as the occurrence of flakes of horn silver in the joints of quartzites at the Isabel mine, near Globe, Ariz., which can be scraped off, leaving thequartzite absolutely barren of silver; and the same ore in the joints of limestone west of Tucson, Ariz., where the surface of the joints gives good assays, while the silver penetrates the blocks of limestone in steadily diminishing quantities for only a few inches, leaving their interior entirely innocent of ore, we can- not invoke the igneous theory, because there are no veins to be injected. The same may be said of the horn silver found in the Leeds mine, near the southeast corner of Nevada, which in many respects is one of the most remarkable occurrences of silver on record. There is no true vein; the matrix or gangue in this case is a nearly horizontal bed of sandstone, in which are found large quantities of vegetable remains, such as wood, twigs and leaves, and it is these which carry chloride of silver in quantity sufficient to make working of the mass not only possible but profitable. In this case there cannot be a suspicion of injection. More doubt hangs over the silver ores in the trachytes or rhyolites of the Calico district, San Ber- nardino County, Cal., which occur in the crevices of a truly eruptive rock; but even here the ores may lie in fissures formed subsequently to the eruption of the trachyte. We are thus compelled to look for some other method by which the fissures, now called veins, have been filled with their mineral constituents. Among those familiar with the subject the igneous theory, 106 PROSPECTING AND VALUING MINES. which held sway for many years, has been generally abandoned as incapable of explaining the greater por- tion of the phenomena. Aqueous Theory. The distribution of ore in veins is of the most irregular character. In some of the gold veins of California the metal is collected in well- defined pockets, containing all the way from a few pounds up to half a million dollars, surrounded by barren white quartz in immense quantities. In other mines we find the ore in threads and stringers, more or less parallel to the general direction of the walls, fad- ing out into the country rock which evidently forms the general mass of the vein, in fact constituting" its gangue. These and other allied facts suggest the modern explanation, which attributes the filling of veins to the circulation of heated waters in the earth's crust. Distribution of Metals, etc., in Nature. Of late years researches into the constitution of sea and min- eral waters has revealed the presence in them of a long list of elements in the form of salts, establishing the fact of their solubility in nature as well as in the chemist's laboratory. In mineral waters the metals iron, arsenic, lithium, csesium, rubidium, copper, zinc and manganese have been detected, along with the elements of earthy minerals which form the gangue of veins, such as silica, magnesia, lime, alumina, fluorine and baryta; besides soda, patash, boron, chlorine, iodine, bromine, phosphorus and sulphur, many of which latter form salts which are excessively soluble. Sea water, according to Prof , Forchhammer, in addi- tion to the chlorides and sulphates of sodium, mag- nesium, potassium and calcium, contains silica, boric acid, bromine, iodine, fluorine as acid, and the oxides of nickel, cobalt, manganese, aluminum, zinc, silver, lead, copper, barium and strontium; and arsenic, gold, lithium, rubidium, and csesium have been dis- covered since Forchhammer wrote. The experiments FlLLltfQ OF MINERAL VEINS. 107 of Prof. Liversidge on the sea water off the coast of Australia give positive results as to the presence of gold. Other investigators also have detected gold in sea water. Daintree reports the occurrence of gold in the ser- pentines and pyritic diorites of Queensland, and the pyritic granites of New South Wales. The nodules or concretions of manganese dredged from the ocean floor by the Challenger expedition showed the presence of nickel and cobalt. Prof. F. Sandberger has announced the discovery of small quantities of silver, lead, copper, nickel, cobalt, bismuth, arsenic, antimony and tin, in silicates such as olivine, augite, horneblende and mica, which are constituents of igneous rocks. Prof. Dana records the occurrence of nickel in the Vesuvian lavas, and also the chlorides of lead, copper, iron and manganese, as forming on the lavas at the craters from the heated vapors; and similar results would probably be obtained at other volcanoes had they been as carefully studied. He also notes the presence in minerals which form a portion of gneiss and granite, of manganese, lithium, cerium, lantha- num, didymium, yttrium, zinc, berylinm, titanium, molybdenum and cobalt; the latter metal also in mica schists with arsenic. J. S. Curtis determined the presence of gold and silver in the silicates of the rocks adjacent to the Corn- stock lode, the silver chiefly in those of the hanging wall diabase or porphyry and the gold in those of the foot wall syenite; and when writing on the quicksilver deposits of the Pacific coast of the United States, Prof. G. F. Becker reports the presence of antimony, arsenic, lead and copper in the underlying granites at Steamboat Springs, Nev. ; and records the fact that these springs are to-day depositing quicksilver, gold, antimony, arsenic, lead and copper. Daubree gives the following list of elements, ar- 108 PROSPECTING AND VALUING MINES. ranged somewhat in the degree of their importance (Maskelyne adds lithium and antimony): iron, mag- nesium, silicon, oxygen, nickel, cobalt, chromium, manganese, titanium, copper, aluminum, potassium, sodium, calcium, arsenic, phosphorus, nitrogen, sul- phur, chlorine, carbon and hydrogen, several of the compounds of which are peculiar to meteorites. The majority of the meteoroids with which the earth comes in contact are exceedingly small, and a weight of 1,000 Ib. is probably uncommon, but when the daily number encountered by the earth, estimated at 20,000,000, is multiplied by years and centuries it is evident that the addition of their contained minerals to the earth's surface is worthy of notice. These minerals, forming part of the sedimentary strata, could find their way into veins without even the intervention of volcanic agency. It is more than probable that the cobalt-nickel-manganese nodules of the deep sea are derived from the meteoric dust falling on its surface. Outside of the eruptive rocks we find ore minerals disseminated* in secondary or stratified rocks, such as slates and sandstones, as well as in limestones, and it is from all of these sources combined that the metals have been concentrated into veins. Underground Circulation. It is evident that water is the active factor in all these changes. We must remember that a considerable portion of the water which falls upon the surface of the earth does not pass off promptly into the rivers, but is absorbed by the earth and rocks, and by the action of gravity pene- trates to depths practically unknown. Of this we have absolute demonstration from its presence in the quartz crystals of deep-origined eruptive rocks, as numerous but exceedingly small bubbles, only visible under a powerful microscope; and from the enormous volumes of steam which are given off by volcanoes in eruption, and which continue to be evolved from the lavas after their ejection. We must not imagine the FILLING OF MINERAL VEINS. 109 crust of the earth as a solid mass, through only the crevices of which water may find a passage; there is abundant evidence that every particle of the earth's crust to depths of which we have any knowledge, and presumably far below, is charged with water, and that there is no substance known which is not permeable by it. Under pressure it can be forced through iron, appearing as a perspiration on the outer surface of the confining flask, and with such a practical demon- stration we are compelled to admit the fact as stated. Heat. While this water at the surface may be cold, we know from the evidence of borings and mining works that the temperature increases with depth from that point near the surface at which it remains sta- tionary through summer and winter alike, so that in the Comstock lode, at the 2,300-ft. level of the C. & C. shaft, the thermometer registered about 150 F., and at the 3,000-ft. level of the Yellow Jacket shaft 170. There is no difficulty in imagining this temperature increasing to the boiling point of water (212) and rising greatly higher, until it becomes so intense that the water may be said to be (l white hot." This heat is not the product of actual fires. It may be partly caused by chemical action, but is more extensively due, in all probability, to the pressure on the earth's crust caused by its steady and constant contraction as it cools, and to the friction from the wrinkling move- ments, The rocks become hot during compression and movement and impart their heat to the contained water, which, aided by hydrostatic pressure, brings it to the surface and it is dissipated in hot springs; or, if such a vent is not made, by volcanic eruptions, or the intrusion of lava into upper and colder strata. Solution, Transportation and Deposition. We are now prepared to understand the action of water in the subsequent processes. We have the waters penetrat- ing the rocks everywhere, the cooler waters descend- ing, the heated ones tending to rise, or being forced HO PROSPECTING AND VALUING MINES. to the surface along the lines of least resistance, such as the fault fissures, by the pressure of other waters or steam. The ability of water to decompose rocks depends on the presence of carbonic acid and alkaline material such as the carbonates of soda and potash, and its solvent powers are increased with a rise of tempera- ture. Its first carbonic acid is derived by rain water from the atmosphere, and the moment it touches the earth it begins its work of decomposition and rear- rangement, picking up and dissolving one mineral and depositing another. Water traversing an open fissure would thus leave a portion of its contents on the walls, both sides alike, as it gradually cooled in its ascent, just as sugar candy will crystallize out of the sugar solution as it is cooled or evaporated, the process of cooling producing the same result as that of evapora- tion, in both cases the liquid being unable to carry so great a load drops it at the first opportunity. In this manner have veins like those of the Wheal Mary Ann lode in Cornwall been formed (pi. 7, fig. 4), a, being chalcedony (silica combined with water), b, glassy quartz terminating in crystals; c, galena; and the central core d, chalytite (carbonate of iron), the depo- sition on both walls being similar and indicating the origin of the minerals. The change in the deposited mineral maj' have taken place either because of the exhaustion of the locality from which it had been col- lected by the water, or from such divergence in the course of the underground flow by disturbances like earthquakes that the material was drawn from a new series of rocks. A similar incrustation of small cavi- ties by waters abounding in silica has formed agates, the banding being due to the changing presence of the coloring material. Compact and close-grained as these agates may seem, they are in reality porous, for it has for centuries been a common practice to boil them in suitable materials to increase the brilliancy of FILLING OF MINERAL VEINS. Ill the coloring of the bands, the change being due to the partial absorption of the material with which they have been treated. When the cavity has not been completely filled, it is either left with a smooth sur- face of chalcedony (which does not crystallize) or lined with crystals of quartz, calcite, etc. In such manner also have opals and other minerals been intro- duced into the oval cavities of basaltic lavas, and thus we have also an explanation of how minerals can be deposited as crystals on the top of each other by just such changes in the character of the circulating waters. Source of the Ore. The source of the minerals thus deposited is to be found in the country rocks of the region, mainly the eruptives, which, as we have seen, contain nearly all, and probably would be shown to contain quite all, of those known; or even from the secondary or stratified rocks derived 'from older igneous rocks, into which the mineral constituents of the latter must unquestionably have been carried dur- ing their deposition as sediment. That lavas have been deprived of their valuable mineral constituents in this way is fairly proved by the experiments of Prof. Becker and Dr. Carl Barus, on the Comstock. The hanging wall of that lode is diabase (in Virginia City), known by the miners as "blue porphyry/' a term which well expresses its appearance when freshly broken. The Sutro tunnel has exposed the structure of the east country (that is, on the hanging wall side) for more than three miles, and developed a series of bands showing plainly the results of solfataric action (by heated waters), with alternating bands of hard blue porphyry. Outside of, and next to the lode, the rock is hard and suggestive of no change, except by the presence of iron pyrites, which is nearly always a product of decomposition, but under the microscope it becomes evident that extensive changes have taken place in it. Its crystalline structure has been modi- fied, the hornblende and augite (silicates) have been 112 PROSPECTING AND VALUING MINE8. altered, pyrite Laving been made out of their iron, and the silver which is present in them further away from the lode has disappeared, the natural conclusion being that it has found its way into the lode through water. Form of Deposit. All veins were not formed in the manner described as occurring at the AVheal Mar} r Ann lode and others similarly constituted. This presup- poses an open fissure, and it does not seem possible that all fissures in which veins have been formed re- mained open during the process. In many it is plain that such was not the case, because they show no true walls, as in the Great Flat lode, Cornwall (pi. 7, fig. 5, and pi. 6, fig. 3), where the ore B is frozen to the dike A, and there is only one wall; or in pi. 6, fig. 1, where the masses are lenticular and not connected with each other (Keystone mine, Cal.); or in pi. 6, fig. 2, where there is no trace of banding, and the hanging wall shows many feeders or stringers not seen on the foot wall. The maintenance of an open fissure in the case of such a structure, as pi. 2, fig. 2 (a generalized cross section of the Comstock lode in Vir- ginia City), would have been an impossibility for the three or four miles of its length, the foot wall having a dip of only 40; but it is equally plain that a slight sliding of the hanging wall on the foot would produce just such cracks as a, b, c, d, accompanied by an im- mense amount of broken material. In many such cases there is no true gangue, the ore occurring in the orig- inal country rock, decomposed it is true, in bands or stringers more or less parallel to the walls, or strike of the rocks which have undergone decomposition, but fading out into the unaltered country rock on either side as at the Great Flat lode, or only on one side, as in pi. 6, fig. 3; while in fig. 1 there is one true wall at the contact line. In these cases we can only account for the presence of ore on the supposition that as the percolating water dissolved and carried away the par- FILLING OF MINERAL VEINS. 113 tides of the rock it left in their place particles of ore, simply making an exchange, and it can easily be understood how this substitution would go on most rapidly and most extensively in those portions of the fissure which had been most shattered during its forma- tion, as the material would have been more largely ground into powder at such points, not only allowing more water to find its way through those portions, but presenting vastly greater surfaces to the action of the water. Thus a cube with faces 1 in. square has a surface as 6 to 1 of bulk, while a cube with faces 2 in. square has a surface of only 3 to 1 compared with bulk. It is at such places that the largest deposits have taken place, and it is thus that "horses" have usually been formed in the lodes; not by masses falling into an open fissure, but by the water circulating through crevices, completely surrounding a block of country rock. We constantly find pieces of country rock in veins completely inclosed in ore, and these are only horses on a very small scale. The Savage mine, at Virginia City, afforded abundant specimens of min- eralized porphyry, suggesting this origin, and those of Monte Cristo, Wash., offer many more illustrations which are totally inexplicable on any theory of large open fissures. Many such veins have acquired slicken sides and gouge by subsequent movements of the rocks, which would naturally follow such lines of weakness, and may even have undergone a partial refilling and reconcentration of their own constituents, some por- tions having been impoverished to enrich others. That such movements have taken place is shown by the crushing of the quartz in some of the larger bodies on the Comstock lode, so that it was known to the miners as "sugar quartz." These examples suggest an explanation which will account for nearly all cases of vein structure, and at- tention in the field will show how beautifully the cycle of changes is constantly in progress, beginning 114 PROSPECTING AND VALUING MINES. with the earliest fracturing of the rocks and the first rainfall, with no cessation to the present time. Rationality of Natural Processes. A moment's thought will show that under any circumstances some such results as have been outlined must have been the outcome of the surface changes of the earth. Even had the original veins been solid masses of gold, silver, copper, etc., their contents would, as they were worn away, have been scattered far and wide through the rocks which were formed out of the earth's first crust, even if that crust itself did not contain them, and the condition of the rocks which we have pictured would have been one of the first results of erosion, and the formation of veins by segregation or substitu- tion must have commenced even in those early days, by the workings of the laws of chemical affiuit3 r , which imply the abandonment by one element of its associate in a compound when it meets with another which is more to its liking under suitable conditions for mak- ing the exchange. How easily these changes are effected may be seen in the occasional action of metallic compounds in the cabinet. Just as the iron pyrite crystals, so abun- dant in some of the gravel mines of California (pi. 11, fig. 3, shows a petrified tree covered with them), drop to pieces and decay with extraordinary rapidity, so specimens of pyrite of the bronze-colored variety from the Glacier mine, Monte Cristo district, Wash., after remaining in the writer's cabinet only two months, were entirely decomposed, the pyrites having absorbed moisture, which combining with the contained sul- phur had produced sulphuric acid, which in its turn had combined with the gangue of the specimen (par- tially altered porphyry), forming glistening salts and rough concretions, not only on the specimen originally attacked, but on the adjacent ones which happened to be in contact with it, however slightly. The amount of moisture absorbed was so great that what remained FILLING OP MINERAL VEINS. 115 of the specimens could not be handled without stain- ing the hands black. On seeing the change the writer remembered extracting from the same vein, in a prev- ious year, samples with the same appearance, having undergone the same changes in place. If then the small amount of moisture which is present in a dwell- ing room can effect such changes, we are at no loss to understand how much greater ones can be effected by nature in her vast underground workshops, with her absolute disregard of the element of time. Ore Deposit* in Limestone. In a somewhat similar way have the greater portion of the deposits in lime- stone been formed, percolating waters eating out pas- sages and chambers, which have been subsequently filled with iron, lead or zinc ores by the waters trav- ersing them. The ability of water to excavate caves, such as the Mammoth Cave in Kentucky, and hundreds of others in all extensive limestone regions, is so well known as to require no further comment, except that the most remarkable feature about them is their sub- sequent filling with large bodies of mineral, usually of only one or two kinds, much less complex in their constitution than the filling of veins; which suggests a different, probably cooler, condition of the percolat- ing water. Such deposits are of the most irregular shape, due to the vagaries of the water which hol- lowed out the chambers, and when the walls are reached they may generally be scraped clean, as the mineral does not usually penetrate the limestone to any depth. PI. 6, fig. 8, is a sketch of such a deposit formed in limestone, on the bedding planes and joints, and controlled only by the lines of flow of the water, as indicated by the arrowheads. Such are the deposits of Wisconsin and Illinois. Fig. 4, same plate, shows the limestone traversed by the dike B, and the arrow- heads the possible direction of the water flow, which if descending, as at A, might form ore bodies as shown in black, or if ascending, as at (7, either as hot or cold 116 PROSPECTING AND VALUING MINES. water under pressure would present a similar structure. Fig 7 shows the structure of the veins at Tombstone, Ariz., being successive strata of slates S, limestone, L, quartzite, Q, and dolomite (magnesian limestone) D, traversed by the quartzose fissure veins A.B, which are connected in the limestone by the flat bodies of rich lead ore, C. In pi. 1, fig. 2, we have at Leadville, Colo., lead ores lying between the limestone flour, the deposits being nearly horizontal, and porphyries for a roof. On pi. 7, fig. 2, we have hematite B, deposited in cavities of the mountain limestone A, at Ulverstone, England. Subsequent to the deposition of the ore it is evident that a further portion of the limestone was dissolved by waters free from iron, forming a later cave which was filled with the clay G, the whole being probably partially worn away before the covering of dirt D was laid down at a much later date. In fig. 3, same plate, we have a similar formation at Al ten berg, Germany, only calamine (silicate of zinc) takes the place of the hematite in the former illustration. B is a body of limestone, lying between the slates A, the zinc ore D filling a cavity of erosion, and the clay C filling a cavern of later date formed after the deposi- tion of zinc ore had ceased. In most such cases it is probable that the filling took place by waters percolating through rocks of later formation, lying above the limestone in which the caverns were formed, from which they abstracted the iron and zinc, only to redeposit them when presented with a more tempting morsel in the shape of lime. Ores Possibly Derived Directly from the Sea. Most chloride and bromide ores of silver and lead are found near the surface, in the joints of limestones and quartzite; it is very probable that such rocks have derived the ore found in them from sea water, when they were a portion of the ocean bottom. In Arizona there are many occurrences of these ores in localities THE FILLING OF MINERAL VEINS. 117 where such a condition has been possible, there being evidences of the former existences of an ancient inland sea. A similar explanation is advanced to account for some gold-bearing conglomerates, in which the gold is supposed to have been precipitated from the ocean, near shore. By a secondary process the gold sparsely disseminated in mud beds at the bottom of the sea might be concentrated in quartz veins, traversing the shales and slates formed by the consolidation of these beds. The ocean-formed ore bodies would, if derived directly, be beds or impregnations and not true veins. Electro-chemical Action. Around many of these phenomena, as around so many of the operations of nature, there hangs a suspicion of the intervention of electricity. The action of electrical currents is forci- bly suggested in the case of native copper mixed with native silver, or of gold crystals deposited upon horn silver; but even if such an agency was active in their production there must have been a previous leaching of other rocks to provide the solutions from which the metals were reduced and crystallized. A Cycle of Perpetual Change. That operations such as we have been describing are constantly going on in nature, and that no extraordinary processes need be invoked to account for the phenomena we see, is plainly evident from the changes which take place in the outcrops of veins and elsewhere. We constantly find incrustations of various salts, such as alum and those of soda and potash, forming on the sides of caves, and even of other minerals on the walls of deserted mines; we secure copper from the waters discharged by copper mines or mines of coppery iron pyrite by allowing it to run over scrap iron, which is destroyed by the acid in the water and copper released ; the pyrite in the outcrop of veins is decomposed under the joint action of air and water, leaving a deposit of rusty iron- stained gaugne, while the sulphuric acid percolates downward to produce other changes; we find surface 118 PROSPECTING AND VALUING MINES. pyrites likewise decomposing, parting with their sul- phur and iron, only to combine with oxygen, and form the red and black oxides of copper, which are richer than the original ore, and in fact are merely concen- trates of ores which may even be too poor to work when the limits of the changes are reached, which is usually where the presence of permanent water pre- vents contact with the air. We also find that many carbonates of lead have a core of galena, which is the sulphide, and know that the conversion has taken place since the deposition of the galena ; and if we look carefully around us we will meet everywhere with alterations going constantly forward. Brought up from the unknown interior of the earth by lavas, the minerals are collected from them into veins, only to be again scattered as the veins are worn away in the general destruction of the earth's surface, and mingled with the fragments of the lavas in sedimentary de- posits, which, as we have seen, ultimately return to granite, only to be intruded into the overlying strata, the wearing away of which uncovers the granite, and the circle is completed. Formation, rearrangement, destruction, reformation and return to the original are the perpetual cycle of the changes in veins, and not only of them but of the rocks in which they are con- tained. Local Limitations. These views afford a natural explanation of the reason why mineral veins are con- fined to certain regions and are not found in all areas of dislocation. We have no knowledge of the appear- ance of the original crust of the earth, as it was formed under conditions which we can never hope to see, but it is evident that all minerals, except meteor- ites, now upon the surface of the globe, in whatever condition, must have been derived either from it or from rocks which have been ejected through it. At the moment these began to decay we have the com- mencement of the whole stratified series, through THE FILLING OF MINERAL VEINS. 119 which, in some form or other, all the mineral constit- uents of the original rock must be scattered, accord- ing to the size of the particles, except those which were perfectly soluble; but always on lines descend- ing seawards. In the course of time these sediments would be again brought to the surface, to be again worn away into new sediments, mixed with the debris of a new series of eruptive rocks, the process being repeated with ever-increasing complexity, but with a constant increase in the metallic contents of the crust, if such were brought from below by the eruptive rocks from time to time. But just as soon as fracturing began, and with it the circulation of heated waters, the concentration of the minute particles into veins would begin, which as they in turn were eroded would furnish particles of larger size to the sediments, and in time these might contain sufficient mineral to form large deposits when concentrated by the circulating waters, even at long distances from the seat of the original eruptive rocks from which the mineral was derived. Such sediments, still retaining the mineral fragments, like the lead and copper-bearing shales and sandstones, can be con- ceived to be still forming. We can now see why all fractured regions are not metalliferous. There must have been an .original area of eruptive or volcanic rocks to start the metal-bearing series, for without this no amount of folding or dislo- cation could have produced an ore vein. We can also understand the spotted or pockety character of many veins; and why there should so often be in a district one strong "mother" vein, as the main fissure would offer more unimpeded channels for the circulation of water than the smaller lateral crevices; and why veins of different geologic age in the same district should be filled with different min- erals, as the source from which the first series was filled may have been exhausted before the formation of the next. CHAPTER VII. INFLUENCE OF ROCKS ON VEIN FILLING. IT is evident that if there is any relationship be- tween ore minerals and rocks, or if, in other words, the useful minerals are more particularly found asso- ciated with some particular rock in preference to others, the knowledge of the facts would be of great value to the prospector, for when he had gained an idea of the rocks of any particular district he would have a general idea of the minerals which he was likely to find there, and could familiarize himself with their appearance, from books or otherwise, and not only know what to look for, but how and to recog- nize them when found. The following imperfect table, compiled from recog- nized authorities, while far from being as complete as could be wished for, undeniably shows that there is such an association of minerals with certain rocks, the reasons for which we may not at present thoroughly understand, but which is not only of interest but of practical importance. The greatest difficulty in preparing such a list is to give equal prominence to all parts of the subject, be- cause while a certain ore maybe found at two separate localities in two different rocks, it may be of no especial value in one of them and of vast importance in the other. It is almost impossible to correlate such differences. One might quote 20 mines in a single district, all having practically the same character, and only one in another district of different rock INFLUENCE OF ROCKS ON VEIN FILLING. 12 1 structure but producing the same metal, thus giving undue prominence to the former mode of occurrence; and it is not always possible to estimate the "personal equation" in the various published accounts, which phrase is understood to include the amount of knowl- edge and accuracy of the writer and preconceived theories unconsciously coloring his views. To overcome these difficulties, and yet keep the table within reasonable limits, a limited selection of cases where the information was full enough has been made from the literature of the subject. The selec- tions are for districts, not individual mines, and though insufficient for a thorough scientific discussion, will be sufficient for our purpose. It does not include iron ore, as that is chiefly found in bedded deposits, not subject to the same influences; nor the minor minerals, such as nickel, cobalt, antimony, bismuth, etc., as they are usually the accompaniments of other ores, and do not form the prominent or controlling mineral of the deposit which imparts to it its positive char- acter, although these may have a preference for one mineral rather than another, and occur most frequently in combination with it. 122 PROSPECTING AND VALUING MINES. Remarks. 111 i 1 g Jg'tf o * ; - s ^Sg -2^ g-g-S ^^ 2-g s fa* ^^ So ^> > ^ QQ O Black clay slates. Talc and serpentine. Talc and serpentine. Quartzose and talcose schists Chloritic, talcose and clay schists. Mica, talc, hornblende and chlorite schists. Mica and chlorite schists. Mica schists and in sheeted walls. Quartzose schists no erup- tive rocks. Between laminae. Schists broken through by cVorite dikes. i I i : i^-d B" 'SS : : : -o 9-, 3 ^ : : Nagyag, Transylvania . . . Sudbury, Ontario Allison mine, Amador Co. Thames district, New Zea Telluride belt, Colo Butte Co., Cal. Berezovsk, Russia Boulder Co., Colo 'ides WyonVg mine. Nevada Co Soaprot mine CalaveraCo Sent"nlmine,BoulderCo., s Wermouth concesXHonc . .. Keystone mine, Amador Cal. Siberia Mariposa Co. , Cal Peshaston Creek, Wash. . e, galena Yavapai Co., Ariz Berezovsk, Russia i 1 c a C Tomoh, Siamese Malay 'nS Maryland 5 C Tolema, South America. Calaveras Co., Cal Principal and Asso Minerals. 9 & \\-\\ I ! : i M Hi ; :i ":: : .o.o..o. Ironpyrite Ironpyrite Ironpyrite Iron pyrite,zincblend i 1 I > \ \ e rocks 1 II P tf 1 Trachyte Diorite Diorite Andesite.., Porphyry.. Porphyry; Porphyry... Porphyry granite Granite or gneiss. . Granite or gneiss. . Granite or gneiss. . Granite line conta Slates.... ' 02 03 CO 05 4-S 4J -1-3 4^ cp to co 02 a 02 CO CO .23 .23 22 2 22 t> o o O2 CC02 Schisms. . . . o . . Schists Schists and eruptiv INFLUENCE OF ROCKS ON VEIN FILLING. 123 ks. -S -S a i & 2 ^ Q a Q H O ^ o III PQ 55 ^j 3 o-o O |;i ii 3 5 PH 1 - 124 PROSPECTING AND VALUING MINES- ri Js-ss&i o| Is 1*4*1 jJl 1 si 1 .S.'SS-S'alSr $0 ^ ' .- S^ &5 ^^ - ? ^yo a 3 pp ^ ^^^ ^g InO O02 INFLUENCE OF ROCKS ON VEIN FILLING. 125 pJie!iMJiliffll 9eg9Sea o o . i a 02 X s .i 6? opO ii si c ^ II S 23 in 55 585 a^ ?s & t t JO! O! .-S.-S N (S3 rr o* 126 PROSPECTING AND VALUING MINES. Remarks. +j 1 Q Vlica slates. Jlay slates. Associated eruptive rocks. Mica schists and gneiss, traversed by granulite dikes and capped with ba- salt. Lodes cut the dikes. 1 a I c3 s s"' 0" r^ Conglomerate foot wall, n ash beds of amvedalordal diabase, n "trap. 11 n "trap. 11 Denticular beds in diorite. [n fissured zones rhyolite near, n beds, ^eins in gneiss and quartzite. Sfear contact of graywacke and diorite, or in the dio- rite. Various schists associated ; a 3 * ' 4* 02 1? Tombstone, Ariz. Salt Lake, Utah.. Maine Connecticut Bohemia Cornwall Monte Cristo, Wa Pontgiband, Fran j 03 3 . 0^3 t- 11 S - a '.2 ;| '-3 tg gOttM Fahlun, Sweden.. Maine Sudbury, Ontario Canelton. Quebec ^ : : : :& 1 W CO i :: % : : : > 33 fV> Principal and ^ Minera LEAD-SlL . Silver, gold Silver . Zincblende and cc . Silver, zincblende . Silver . Ziucblende and si . Silver, zincblend pyrite. COPPEI . Native . . 09 C ii 02 33 ii 11 Jb : : :S 1 C i^ sa "c3 & fill !|| | ii S'E3 I I O D 33 ^3 ^.S: ^ s j|f i 11 o> ta t cc - -M "fcib I -2 60 1 ^ aaaa "3 '3 ft g S ^ 2 E cow K INFLUENCE OF HOCKS ON VEIN FILLING. 1 n or near to the Carbonifer- ous limestone. Another S S ft c 3 I |co "3 ' z *5 ; l 1^ IS gil i i w p i ^ in n ii 2 ii if i if si. S . rtlllf |8^2 s g.3lll|: M VF | |3Sg .5| <^-sJ >! |1s|l|ii jiii :S laStSrii Sifll >! J'S^fi-a-'SS SgSSS ) QPQ I^M PQcC Small veins, n granitic gneiss, n lime at contact of dikes cutting lime and granite, ncluding dolomites, ncluding dolomites, ncluding dolomites. i tjj I s il oo i 1 4 1 S >> : .S T ^ I .H 5 J5 "'1 1 5 j?T3 5 ft M " 2 5 -^ " ^ ^ r/^ O CC J-i 1 dj"* w.s * a ^ 2 5 o S 3 o^ o" 5 OS55 HP3 OJO C .... Maryland .... Ammerberg, Sweden .... Southwest N. Mex .... England and Belgium Connecticut .... Wis., Mo., Iowa and Ills... Associate Is. ^ cs T3 *-< ll i i WH w '. H : : o w co rl 9 P : : : : : : S : 8 : CO P< fcn :fe d : a Ih Ml f 1 ( Oxidized or o . . . Oxidized 01 S =S 8^3 T3 I Q CO 73 Oj i!J ll! o ;O t>^;o 111 1 I o 81: : : i : : : : :a : : 8 i : : I ! : " ; & Granite lime Limestones . . Limestones . . w : : : : :-g-g :^3coco coco wSS CCDO) CDCD 5353 ^oo oo oSS | ^j*3 4j4j *^^^ 73 Qfl_; flfl flflP "^ S : : : 1 $$$ &* c a a 000 Jit 111 s ... OOPn JJJ 128 PROSPECTING AND VALUING MINES. INFLUENCE OF ROCKS ON VEIN FILLING, 129 il 0)^3 >0 *%S ? Si's s|SI ;- H^a.S O o *- f-> SSrf .S< 3 I^' 3* ! o>^? 1 3 1 .... 3 q 4 8 5 Zinc 1 Tin 5 1 2 7 1 2 6 tl By further condensation we have the following table : COUNTRY ROCKS BROADLY GROUPED. Metals. Granite, Gneiss, and Syenite. Sedimentary Rocks. Associated with Eruptive Rocks. Totals. Gold. 3 15 16 34 Gold and silver.. 1 2 3 Silver 2 5 11 18 Lead 3 16 25 Copper 3 11 7 21 Zinc 2 5 1 g Tin 5 2 1 $ Chrome 7 7 Manganese 1 2 2 Mercury 4 6 10 19 68 50 137 * Probably remains of beds of lime, i All in belts of hot springs. INFLUENCE OF ROCKS ON VEIN FILLING. 131 The rocks in the foregoing tables may be further classified according to the amount of silica or quartz which they contain, into three groups: \. Highly silicious: Granite, gneiss, mica schists, sandstones, conglomerates, quartzites, eruptive rocks, and some limestones. '2. Moderately silicious: Chlorite, talc and clay schists and shales, conglomerates in part, and some lime- stones. 3. Scarcely silicious: Limestones and dolomites. Examining the metals in the foregoing list we find in the case of Gold. Twenty-six occurrences in rocks abounding in quartz (silica) out of the 34 localities, and in some of the remainder the same conditions probably exist, as many shales and conglomerates are highly silicious. Only one occurrence is noted with limestone and in this case the foot wall of the deposit is granite. Gold and Silver. All three occurrences are in rocks abounding in silica. Silver (aside from silver-lead ores which are classed as lead) occurs in 13 very quartzose rocks out of 18 instances, and the remaining 5 are probably silicious, as many limestones are highly silicious. Copper also occurs with 18 very quartzose rocks, and probably with 19 out of the 21 localities, if not more, as the Clifton deposits are differently described by two writers, and the other limestone locality may carry much quartz. Lead, however, occurs in the quartzose series in only 10 out of 25 localities, the remaining 15 being in association with limestones, while some of the former may have lime to some extent as a minor constit- uent. Zinc shows 6 out of 8 times as an associate of lime- stone and only twice in the quarfczose group. Tin. All 8 of the occurrences are in quartzose rocks. 132 PROSPECTING AND VALUING MINES. Chrome. All 7 localities are in serpentines, usually associated with gneissic or hornblendic rocks. Manganese is associated with both extremes of rock. Mercury. All 10 localities are in highly metamor- phosed rocks of various kinds, but nearly all are asso- ciated with recent eruptive rocks and hot springs. The relative importance of these occurrences is best tested by the output commercially of the different metals. Tested in this way, the highly silicious rocks produce the bulk of the gold, silver, copper and tin ; the non-silicious or true limestone rocks, the bulk of the lead and zinc, and rocks which on decom- position yield both silica and lime, give complex ores of gold, silver, lead, copper, zinc, tin and manganese, with many other less prominent metals. Metals Associated With Each Other. Gold and silver are so intimately associated in nature that all gold may be said to contain some silver; and most silver ores carry gold, from mere traces up to impor- tant values. Gold containing a large proportion of silver is pale in color and is sometimes called "elec- trum ;" while some native gold-silver alloys are almost white. Lead and silver are also so related that lead ores as a rule carry some silver, if only a trace, and from that up to large amounts in value, though not in bulk, without any special change in their outward appear- ance. Lead and zinc are also intimate associates, as are also lead and antimony. Copper and silver, or copper, silver and gold, often go together. Iron and manganese, or iron and chrome, are fre- quently associated. Nickel and cobalt are closely related, both chemi- cally and in occurrence. Arsenides and antimonides of other metals are often found together, and either or both with sul- phides. INFLUENCE OF ROCKS ON VEIN FILLING. 133 Country Rock and Gangue. The ore minerals proper usually compose only a fraction of the whole vein filling, the gaiigue minerals being present in larger, often very much larger quantity. The rocks through which the underground waters pass must con- tain material suitable to form this gangue silica for the quartz, lime for the calcite, fluorine for fluorspar, sulphur for the sulphate minerals, etc. The gangue minerals are closely related to the metals and true ore minerals (as quartz to gold, calcite to galena, etc.); hence the connection is really threefold country rock, gangue, ore. Relation of Eruptives. While eruptive rocks are frequent accompaniments of ore, they are not abso- lutely essential to its presence either in the silicious rocks of Otago, New Zealand ; or the sandstone reefs of Bendigo, Australia, or the non-silicious limestones of the Central States in America. In only 50 out of 137 cases are eruptive rocks mentioned in connection with the ore deposits as being of possibly prior origin, or about 36%, while in 68 cases, or about 50%, there is no apparent connection of either eruptive rocks or granite. Possibly eruptives existing in the neighbor- hood of ore deposits, but not actually contiguous, are sometimes overlooked or not reported. There are cases in which the metal in the deposits undoubtedly appears to have been derived from them. But outside of these instances there are others where the outbursts of eruptive rocks have simply produced the necessary conditions of heat and fractured rocks, furnishing waters of the requisite temperature and pro- viding ample facilities for their percolation through materials so crushed as to be easily soluble. Similar results have been obtained in other places, without the aid of eruptive rocks, by the enormous pressure involved in the complicated folding which we see in such cases as the sandstone reef at Bendigo, Australia, or the abruptly folded strata in Nova Scotia, 134 PROSPECTING AND VALUING MINES. so that it would appear that any cause which will pro- duce heated water and fractured rocks is sufficient to furnish the conditions for vein filling, the material for forming the deposit being drawn from any one or all of the rocks indiscriminately through which the water has been circulating, whether above, below, or along- side, near to or at considerable distances from the point of final deposit; and that this place of final deposit is largely determined by the character of the rock through which the water may be circulating at the time it is compelled to part with some portion of its mineral burden, and not by the character of the cause which produced the fissures, or the nature of the associated eruptive rock, unless the ore is deposited in thi t rock itself. The following extracts strike the keynote and indicate a line of examination which will explain nearly all, if not quite all, the phenomena of the association of minerals with each other, and the rocks in which they occur. Speaking of the ore de- posits in the Potsdam series of rocks in South Dakota, Dr. F. B. Carpenter says: "These ores are in some sections, almost exclusively gold-bearing; in others, they carry partly gold and partly silver, and again in other places the silver predominates." "It seems as though the porphyry at Bald mountain brought mainly gold ; at Buby basin, only a few miles distant, gold and silver in nearly equal quantities (in value); while at Galena, 12 miles distant, silver-lead predomi- nated. That is, broadly speaking, gold predominates in the quartzites, but gives place to silver as we ap- proach the more calcareous portions forming the upper parts of the Potsdam; while in the massive limestones such ore bodies as are found, like the Iron Hill, carry exclusively lead and silver, yet the porphyry is in all instances the same." Variations in the Mineral Solutions. But in following up this line of argument we must remember that all waters will not be charged with the same mineral, INFLUENCE OF ROCKS ON VEIN FILLING. 135 or the same water always with the same mineral, as their contents must vary with the nature of the rocks from which they draw their supply, and consequently they can only deposit what they have in solution for the time being, and may carry that for long distances for want of a suitable precipitating agent. They may have only one or many minerals in solution, but at any rate we are prepared to understand the occurrence of gold in the joints of porphyry, of silver in the joints of quartzite, of lead and silver in the seams of lime- stone, and why the character of the ore should change so suddenly when a vein passes from one series of rocks to another, as for instance from a silver-bearing galena with zincblende and iron pyrite in decaying porphyries with lime feldspars, or a gold-bearing arsenical pyrite in the underlying granite; from copper in silicious slates to tin in a still more silicious granite, where also the character of the mica (white mica being common in tin-bearing rocks) appears to have an influence, or to be, like tin, a result of the same influence; or from deposits of galena in limestone to barren material in the intercalated beds of " toad- stone" (an ancient eruptive rock), as in the lead deposits of Derbyshire, England. Influence of the Country Eocks. The practical miner, however, is not so much interested in the scientific explanation of such sudden changes, but he is very materially interested in the fact that they do occur, as they may involve serious and costly changes in the character of the reduction plant, or a loss of the vein altogether, as at the Stonewall Jackson mine, Arizona, where the native silver found in the surface porph3 r ry disappeared altogether when the underlying granite was reached; or, as on the Comstock lode, when the fissure left the syenite-porphyry contact and passed into the underlying syenite, where it presented only occasional bunches of gold ore, instead of the silver deposits of the eruptive contact levels. 136 PROSPECTING AND VALUING MINES. The lesson inculcated is the desirability, to say the least, of a thorough examination of the line of outcrop of the deposit under consideration, before erecting reduction works, not only to avoid the necessity of change, but to determine the probable extent of the ore-bearing ground ; for if the ore be confined to a cer- tain class of rocks in any particular district, the extent to which such rocks are developed is an impor- tant element in the future of a mining camp, and must largely govern the amount of money which it will be wise to invest in means of transportation, etc. The views here set forth also explain why long belts of country produce similar ores, while parallel belts at no great distance often only a few miles may pro- duce a totally different series over a like extent of country ; or why the ores on one side of a mountain range should present a totally different appearance from those on the other, where both series have been subjected to the action of the same eruptive rocks, or to no such action on either side. It is simply because they occur in parallel belts of rock of differing com- position, the outcrops of which are presented to us on the flanks of the mountain ranges in which they lie, more or less parallel to the general summit of the range or axis of elevation. Thus below the free gold belt of the mother lode in California which, however, is not a lode in the true sense of the word, but a belt of gold-bearing rocks, in which many deposits occur roughly parallel to the general strike there lies in the foot hills a band of copper-bearing rocks of equal extent north and south, while higher up in the range there is a belt of limestone country with which are associated ores of a more complex character, galena as might have been expected making its appearance. Again, just as the ancient schists of the Carolinas and Georgia furnish ores of the same character, over a distance of many miles, so do the ancient metamor- phosed rocks of the Cascade range, in Washington, fur- INFLUENCE OF ROCKS ON VEIN FILLING. 137 nish for miles on the western slope complex ores of very uniform character in each member of the rock series, but differing entirely from those on the eastern flank of the same range. It is for such reasons as these that geological surveys may be of very great utility, if they can be made be- fore the districts have been exhausted and all the thousand and one experiments and failures have been tried and made; but of no direct and local value what- ever if undertaken when the mining camp is wellnigh deserted, although perhaps useful in showing a com- parison with other localities. CHAPTER VIII. MINERAL DEPOSITS OTHER THAN VEINS, Succession of Formations. -As we have seen in dis- cussing the filling of veins, it was not necessary in their case that the filling should have been derived from rocks which lay at a greater altitude than the deposits which were being formed, although without doubt a large portion of them may have been so situ- ated, but in the formation of bedded deposits in strat- ified rocks only a very insignificent portion are derived from springs, thermal or otherwise. Deposits are laid down on the top of rocks already formed and covered up by others of a later date. While these latter must of necessity lie conformably on the deposit, or cover it horizontally, those on which the deposit lies were not necessarily so. A mineral formation may follow in orderly succession as one of numerous layers, or it may be laid down on the upturned edges of older strata, which have been tilted up and largely worn away before they sank again beneath the water and received a new covering. In pi. 2, fig. 1, the strata E, G, D, lie conformably on each other, but un- conformably on the tilted series A. If there be also such a series as B we infer that it was laid down on A\ that a gradual horizontal upraise brought B out of the water and permitted the destruction of most of the series; and that a subsequent depression, without tilt- ing, allowed the deposition of E, C, D, which are also said to be unconformable to B; but it is evident that it will be much more difficult to trace the true rela- MINERAL DEPOSITS OTHER THAN VEINS. 139 tionship between E.C.D and B than between #and A, or between E, C, D and A. The most important deposits to us, outside of clays and those which have formed building stones, are those of coal and iron ore; salt, gypsum, carbonate of soda, niter, and the allied minerals. The action of water is evident in the formation of all these, as the agent by which the material has been collected, except in the case of coal, whether they have been made by the ocean, to which the contained minerals have been carried by streams from higher altitudes, or in inland basins long since dried up, to the lower portions of which other rivers have carried in solution the mate- rials derived from the ridges bounding the basin, and which are now in process of decay. Solvent Capacity of Water, and Evaporation. We have seen previously that heated waters have the power of holding in solution a larger quantity of any given material than those of lower temperatures, and that in cooling they are compelled to deposit a portion of their load, as in the case of hot springs, w r hich build up masses of sinter around their orifices. The quantity of mineral matter which such springs may bring to the surface will be better understood by the statement of Prof. Kamsay that the hot springs at Bath, England, discharge annually sufficient solid matter to make a column 140 ft. high by 9 ft. in diameter. But whether hot or cold there is in any case a point at which waters have absorbed and hold in suspension the maximum quantity possible. This is called the saturation point, and such a solution is said to be saturated. If more solid matter is added to such a solution it falls to the bottom undissolved, or if the amount of water be re- duced by evaporation the same result follows; a por- tion of the dissolved matter is squeezed out of the solution as its particles contract on each other, and falls to the bottom. The incrustation on boilers is the result of just such a process, and the principle is 140 PROSPECTING AND VAL UING MINES. applied artificially in the production of salt from brine. In nature we see it in the drying of the ground after rain by the winds and sunshine, the ground losing and the air absorbing the moisture; but few persons realize that the loss from large reservoirs is equal to 36 in. annually over the entire surface; and is still greater in shallow waters, where, in excessively hot and dry climates, the loss by evaporation may rise to as much as 1 in. in 24 hours, still going on even dur- ing the night. So great indeed is this evaporation in the deserts of the Great American basin that all the rainfall is taken up in this manner, the numerous lakes having no outlet, but varying in size from month to month, and day to day, as the rainfall or sunshine gains the mastery, shrinking in hot and dsy and ex- panding in cool or wet weather, and always maintain- ing an area which is just large enough to enable the evaporating agencies to take up the exact amount of water flowing into the lakes. The popular notion of subterranean outlets for this water has no foundation in fact, as evaporation is sufficient to account for all the phenomena. But in this process it is only the water which is lost; whatever minerals or solid matter it brought down from the mountains into the lakes is left there, accu- mulating slowly but surely, no matter how small the amount may be per gallon of water, until sooner or later the saturation point is reached, and a deposit begins to form of whatever salt may be least easily held in solution, if there be more than one. For a time the annual influx of water may be able to redis- solve the precipitated portion, during the more rainy part of the year, but in the course of time this precipi- tate will exceed in quantity the amount soluble in the annual inflowing water and a permanent deposit will begin, the surface of which will suffer a partial re- solution annually, but the mass itself steadily increas- ing in bulk. In this inauner have gypsum, rock salt MINERAL DEPOSITS OTHER THAN VEIES. 141 and carbonate of soda been deposited from saline waters; gypsum from sea water, saturated with the sulphate of lime, but able to hold all its chloride of sodium (common salt) in solution ; salt from similar waters by evaporation, the salt in such cases contain- ing the small amounts of sulphate of lime and other minerals which may be in solution and which consti- tute its impurities. Both of these substances are therefore purely mechanical precipitates. Natural evaporation has in this way produced enormous masses of rock salt, like those of Cheshire, England, and Cracow in Poland, both of which are extensively opened by underground works; or that at Sperenberg, near Berlin, which has been penetrated by an artesian boring to a depth of 3,907 ft. without the bottom hav- ing been discovered ; or those which are exposed on the surface on the Bio Yirgen (or Virgin Biver) in Nevada, which are described as follows: "A formation exists at this point composed of rock salt resting on, and to some extent intermixed with, sedimentary rocks, and of such magnitude that it may be said to constitute a notable portion of the hill in which it occurs. More than 60% of this entire mass appears to consist of hard rock salt, having the transparency of clear ice, and containing over 90% sodium chloride. This formation extends along the eastern bank of the Yirgen, presenting a bluff face to the stream for a dis- tance of 25 miles or more, and reaching in some places a height of several hundred feet. " These deposits are so enormous that we might even be disposed to question the power of so simple a cause to accomplish the results which are still, however, being reached at Carmen island in the Gulf of Cali- fornia and elsewhere, but the following description of the Karaboghaz sea (from Sir A. Geikie) will show them to be not only probable but possible: cc Along the shallow pools which border this sea (the Caspian) a constant deposition of salt is taking place, forming 142 PROSPECTING AND VALUING MINES. sometimes a pan or layer of rose-colored crystals on the bottom, or gradually getting dry and covered with drift sand. This concentration of the water is still more marked in the great offshoot called the Kara- boghaz, which is connected with the middle basin by a channel 150 yds. wide and 5 ft. deep. Through this narrow mouth there flows from the main sea a constant current, which Yon Baer estimated to carry daily into the Karaboghaz 350,000 tons of salt." This amount if all deposited would cover 250 acres to a depth of 1 ft. Such deposits belong not only to the open sea, but mostly to inland seas or lakes which have originally formed a portion of it, and consequently partook of the general diffusion of the salts which are discharged into it by the rivers through its entire bulk. The deposits which result from the concentration of min- erals in isolated fresh water lakes will naturally par- take somewhat more of the character of the salts fur- nished by the rocks undergoing decomposition, and which are gradually water-borne to the deepest depres- sions or sink holes, there to be evaporated and con- centrated or deposited. To such causes can we cer- tainly attribute the lakes furnishing the carbonate of soda and sulphate of soda so common in the desert regions of Nevada, Utah and Wyoming, and the salines producing borax, and the nitrates of potassium (saltpeter) and of sodium (Chili saltpeter) in the same regions and also in the deserts of South America; and the bitterness of Mono lake and other waters due to the presence of sulphate of magnesia (Epsom salt). With such an origin it is plain that the efflorescence or crusts of these easily soluble salts are to be sought for mainly in arid regions, where the rainfall is not sufficient to re-dissolve them after formation, and that chiefly during the hottest portion of the year when evaporation has done its work most thoroughly. The presence of these salts in streams need not be per- MINERAL DEPOSITS OTHER THAN VEINS. 143 ceptible to the taste, for even good drinking waters may carry an average of 20 grains of solid matter per gallon in solution, but the constant accumulation of even this small amount, if carried on for a time suffi- ciently long, will produce all the phenomena we have been describing. Alternate Evaporated Deposits. It must not, how- ever, be supposed that these deposits are always uni- form in quality throughout. In many localities they consist of alternating beds of salt, gypsum and clays; or carbonate of soda, salt, gypsum, Chili saltpeter and boracic materials with clay partings, laid down as one or other of the materials predominated in the water supply, owing to changes in the character of the rocks from which the salts were drawn, and varying accord- ing to relative solubilities. It can also easily be un- derstood that they will thin out in every direction round their boundaries, which are also apt to be mixed with impurities blown into the lakes from the dry sandy wastes, or forced in by the sudden rush of water caused by cloudbursts. Sediment Mineral Deposits. Besides the mineral salts carried in solution by water, it is likely that some bedded deposits owe a portion at least of their contents to particles of mineral brought in suspension by flowing water and deposited, like other finely divided suspended matter which goes to form shales, slates, etc., when the current was checked and no longer able to carry them. .Beds of Iron Ore. It is evident that in all these cases there is not necessarily any chemical action tak- ing place, after the water has once absorbed the material to be deposited, but such is not always the case in the formation of iron deposits. While some iron ore is formed in lodes, or cavities in limestone as a deposit from ferric waters (waters carrying iron), probably the larger bulk of iron deposits have heen thrown down in beds in the waters 144 PROSPECTING AND VALUING MINES. of swamps or lakes, through the absorptioD of oxygen from plants and diatoms (infusoria) accompanied by the liberation of hydrogen and carbon in the shape of marsh gas. Bog iron forms in marshy ground in such a manner at the present day, out of waters which have become charged with iron, col- lected from the sands and rocks through which they have traveled ; and where the accumulations of nodules and concretions have been removed, the formation of others shows that the process is still in action. Such deposits will naturally be most impure round their margins, as in the case of coal and the minerals just under consideration, and may range from mere mix- tures of sand and iron, or ironstone and clay, up to iron ores of great purity, according to the conditions under which they were formed. True, heat and pres- sure have modified many of them, eliminating the water from the brown, and converting them into red hematites, which by still further changes may have been altered into magnetites. Many of these deposits covered so large an area that now that they have been uplifted along with the rocks which contain them, and have lost a portion of one of their edges by erosion, they present the appearance of true contact veins, and can be worked as such ; but from the difference of their origin they are likely to maintain a uniform thickness for much greater lengths and depths than true veins, and also to retain a more uniform constitution. Beds of Gold, Copper, Silver and Lead Ores. The formation of beds of conglomerates containing gold, as in South Africa, or copper as in the Lake Superior region ; of sandstones containing copper as in Europe, or silver as at Leeds in southern Utah, or shales con- taining galena, has in nowise differed from the forma- tion of similar deposits in which minerals of value have not been found. It is only the presence of min- eral in them which calls for attention. The native MINERAL DEPOSITS OTHER THAN VEINS. 145 copper in both conglomerates, sandstones and amyg- daloidal traps (or ancient eruptive rocks) of Lake Superior may have been subsequently introduced by the infiltration of waters carrying copper in solution, from which the copper was abstracted by the reducing and transforming agency of the iron in the rocks, or in other cases may have even been introduced at the time the beds of sandstone, etc., were laid down, and the same may be said of the grains of galena in shales, but it must be confessed that the true origin of these metallic or metalliferous grains is wrapped in some obscurity as regards the question of time. The same may be said of the chloride of silver associated with the vegetable remains in the sandstones at Leeds, the difficulty here being as in the other cases to account for the presence of mineral in one bed of sandstone and its absence from other similar formations. We can only suggest that in the Leeds sandstone waters carrying silver in solution were compelled by the nature of the stratification to traverse the band of sandstone, before its vegetable remains had become petrified, and in that condition acted as reducing agents on the argentiferous waters; or that the bed of sandstone was formed under such circumstances, from rocks containing silver, that the sediment was a com- pound of both materials, which subsequently under- went a chemical rearrangement through the action of percolating waters, in which the organic remains played the part just assigned to them, just as organic matter like charcoal will precipitate gold from its solution in chlorine. The useful metals other than gold, iron, copper and manganese (which is also precipitated from sea water by organic remains such as bones), are, however, derived to so small an extent from ancient beds that their occurrence in them is more of a mineralogical curiosity than an important problem for the miner, who is chiefly interested in being able to distinguish 146 PROSPECTING AND VALUING MINES. between a bed and a true vein, on account of the greater certainty of permanence in the former and the probabilities of its position underground. Dip of Mineral Beds As a bed belongs to a series of strata which may have been uplifted, so that a por- tion of them has become visible on the surface as parallel outcrops, there is no certainty that the appar- ent dip of the strata (that is, what can be seen at any one point of exposure) will be the permanent dip of the entire deposit. The probabilities are altogether against such a supposition, and in favor of a flattening out as the dip is followed downward toward what must be the center of the basin, of which we see portions of the rim only as in the case of the strata seen on the left half of pi. 3, fig. 5, or the right hand halves of pi. 4, figs. 2 and 3. It does not, however, follow that all the strata exposed will reappear when the other edge of the basin is found and explored, because some of them may have thinned out and disappeared in the intermediate space, and their place be occupied by others, or the other edge of the basin may not be seen on the surface at any point, being covered up by rocks belonging to later epochs. When strata thus dip together toward each other, forming a trough or basin, they are said to be "syn- clinal;" when they dip away from each other, as in the left hand side of pi. 4, figs. 2 and 3, or like the two sloping sides of a roof, they are said to be "anti- clinal;" In the former case they may rapidly pass out of the limits of a surface claim and enter adjacent ground, in which they may be reached by shafts. In the latter case, they may pass out just as rapidly if only a small portion of the top of the anticlinal fold has disappeared and the location be based on an out- crop of the flat top of the arch or fold; but as more of the fold has been removed the dip will apparently be steeper, reaching its maximum half way between the top of the fold and the bottom of the adjacent trough MINERAL DEPOSITS OTHER THAN VEINS. 14? if the folding be perfectly regular; such, however, is scarcely ever the case, but the principle involved is the same, as can be seen by a study of pi. 3, fig. 5. Outcrops of Folded Mineral Beds. The peculiarities of the outcrops of bedded deposits, when there has been folding of the strata, are well illustrated in pi. 4, figs. 1, 2, 3 (after Geikie), and should be carefully studied by those making locations of iron or coal deposits, as they may lead to wild conclusions as to the amount of ore or coal in the surface exposures. Figs. 2 and 3 show how, by lateral pressure, the beds laid down horizontally have been squeezed until any one of them presents the appearance of a piece of corrugated iron, or the troughs and crests of a series of waves. By the wearing away of the surface of such a folded mass the edges or outcrops of the different strata would be exposed as in fig. 1, of which fig. 2 is a cross section on the line O H, and fig. 3 on the line C D B. B forms the synclinal and A, A, the anticlinal fold of the exposure, the different beds of which are numbered so as to be recognizable in each of the figures. The dotted lines in figs. 2 and 3 indicate the position of that por- tion of the folds which has been worn away. Now, if we suppose the heavy black line between 12 and 13 to be a deposit of iron ore, it is morally certain that the majority of prospectors would report two veins forking at B y pi. 13, fig. 1, when instead of two veins, presum- ably dipping into the ground to unknown depths, there is merely a trough lying between the two out- crops, the boundaries of which can be absolutely measured and the area calculated similarly at A 4, fig. 1, two veins would be reported forking in a similar manner, whereas it is merely the same sinuous dipping away in all directions to unknown depths, and conse- quently more extensive than the beds B,B, but more difficult of access, and to be found below B, B if not buried too deeply under the strata 5 to 12 inclusive, to be reached by shafts. These remarks are intended 148 PROSPECTING AND VALUING MINES. to direct the attention of the prospector to the neces- sity of ascertaining the dip of such discoveries at the earliest possible moment, as a simple matter of self- protection, so that he may locate the requisite adja- cent ground and prevent others from gathering the larger share of the fruits of his labors. Even the simplest tilting of a series of strata, combined with exposure of the outcrop by one stream running with the dip and another across it, may present the appear- ance of cross veins, particularly if some portions of the outcrop are covered with debris in such a way that it is not visible for its full length. Caves, etc. Where ore is found outside of fissure veins or contacts, the influence of the rock on the form of the deposit is yet more strongly marked. We have noted the influence which slates exert on lodes, con- verting them rather into metalliferous bands of rock. Limestones stamp their character upon the ore bodies by the formation of chambers connected together by thin seams or pipes. However irregular the series of chambers may be, they must have been formed by cir- culating waters (descending in the example shown by the arrowheads in pi. 6, fig. 8) which followed the bed- ding planes or joints, and we must consequently take these as our guides when searching for the continua- tion of an exhausted chamber. In this connection it is instructive to note the great similarity between a map of the workings of the lime- stone contact lodes of Leadville and one of tortuous chambers of the Mammoth Cave in Kentucky, carved out of limestone by the action of water, the only apparent difference between them being that one set of chambers has been filled with ore and the other has remained open. The latter fact is further of interest as showing that it is possible for underground open- ings of large size to exist, as opposed to the theory advanced by some w ? riters that such caves are impos- sible along the lines of a fissure on account of the MINERAL DEPOSITS OTHER THAN VEINS. 149 enormous pressure of the surrounding earth mass, and that consequently all veins must be formed by gradual substitution of one mineral for another, at the time of removal. Many deposits are, however, undoubtedly formed by the substitution process. Coal and Auriferous Gravel Beds. Discussion of these deposits is reserved for Chaps. XY and XVI, respectively. " Masses" are noticed in Chap. IV., p. 81; "gash veins" and "segregations" in Chapter V , p. 95. CHAPTEB IX. PROSPECTING. Discretion in Taking up Ground. Fortunate is the man who has the instinctive ability to recognize a "mine" when he sees it, and the courage to forbear locating every little seam of ore he may encounter. Nearly every prospector is "location poor;" loaded up with so-called mines, the bulk of which should never have been located; which he is confessedly unable to work, and many of which were simply considered "good enough to sell" when the notice of location was pasted. As a general thing, nothing is worth locat- ing, and it is only in exceptional cases that anything is worth working, which has not a first-class surface showing either in quantity or quality of ore. "Ex- tensions" of good and proved mines may be excep- tions. Accurate Observation and Description. It is a com- mon remark among prospectors, when the surface showing is not particularly promising, that it is only necessary to gain depth to make a mine. We shall soon see that there is no foundation for such a state- ment, when we come to consider the lesson of the out- crop. But first let us look at the points which a pros- pector should note about each of his locations as they are made, so that he may be able to intelligently explain their condition to those whose aid he may desire to develop them, remembering that all ques- tions which can be answered positively should be so answered, and that on all other points an underesti- mate is infinitely better than an overstatement. If a PROSPECTING. 151 man examining a mine for investment finds the repre- sentations honestly and accurately made, the first im- pression (always an important one) is favorable and likely to remain ; but if first one discrepancy and then another is encountered, a feeling of distrust is created which may break off pending negotiations, while at the same time there has been no intention on the part of the owners to make a rnisstatement of facts. The trouble frequently arises from the use of terms in a loose way, so that they convey to the hearer a totally different impression from that intended by the speaker ; or it may be altogether from a want of knowledge or misapprehension of the meaning of certain facts. POINTS TO BE DETERMINED. 1. DISTANCE FOE WHICH THE VEIN on DEPOSIT CAN BE TRACED. Not infrequently we are told that the vein can be traced a mile, when in reality there are only a series of isolated outcrops in a more or less straight line, with intermediate barren or apparently barren spaces, often of considerable extent. Strictly speak- ing, the distance for which the outcrop can be followed without a break is all that should be called traced, but if the vein lie at the contact of two different kinds of rock, and on following this line of junction, even when no vein matter is visible, a second outcrop be found on the contact, both outcrops may fairly be con- sidered as on the same lode. The same will be the case if the vein is formed on the wall of a dike, in which case all ore bodies lying on the same side of the dike may be called parts of the same vein. But as it seldom if ever happens that the vein for its whole length is ore-bearing, the distance the vein itself can be traced is of vastly less importance (except as indicat- ing its strength and probable continuance in depth) than the distance the ore body, the really essential part of the vein, can be followed unbroken. This length should be determined even if it takes some trouble. 152 PROSPECTING AND VALUING MINES Following Dikes and Contacts. In tracing an out- crop, or rather a vein, nature offers many indications. If following a dike, the latter is generally much larger than the vein and not infrequently harder than the rocks which it traverses, standing up above them, and can be taken as a guide. If the vein is on the contact of two rocks, and covered in places with earth or debris, it is only necessary to locate outcrops of the rocks on each side of the contact, and the search may safely be confined to the space between them. Nar- row trenches through the surface dirt, run across the general line of the lode, will easily locate the contact and disclose the ore if it exists. The process is called "costeaning" by the Cornish miners. Vegetation as a Guide. Sometimes the vegetation on the two different rocks, especially when decidedly unlike in composition, is so different that the line of contact may be traced by it alone. In open countries free from heavy timber, like Arizona, this is strikingly the case. Probably the most distinctive vegetation in those localities is the various forms of "yucca, " of which the "Spanish bayonet" is a sample; and the "ocotilla" (o-ko-te-ya). The yucca is confined to the granite or quartzite rocks, evidently liking a soil abounding in silica (quartz); the ocotilla is as de- cidedly confined to the clay-slate regions, the line of contact being often drawn on a hillside by these two plants as if defined by a fence; while the cactus fre- quents the limestone outcrops and the areas of erup- tive rocks. In other words, for successful growth, the yuccas require quartz, the ocotilla clay, and the cactus lime. In the broad washes or beds of summer tor- rents, called "arroyos, " where the rocks are mixed, all three may be found growing if the debris is of a suitable character. A fissure may also be defined by the vegetation growing on it being different in character, or a line of contact may be traced by the same means, as in Cali- PROSPECTING. 153 fornia, where the rim rock of the gravel channels, even where covered and obscured by dense brush (chaparral) can be followed along the mountain side by the elderberry bushes, the white flowers of which are very conspicuous in the gray brush in spring. These bushes require permanent water and have located themselves along the bed rock rim where the water in the gravel flows over it or on the top of the pipe-clay just below the lava cap. Springs. -A lost vein may not infrequently be picked up again by examining the springs along the line of its general direction, as the extent of the fis- sure converts it into the most available underground water-course, which gives up its supply as a spring, if a ravine has cut down across it, to the permanent water level of the lode. 2. THICKNESS OF THE VEIN. Here again there is often a confusion of the vein and the ore body. It is the thickness of the latter which is the important item to the intending investor; the total width of the fis- sure is only of interest as suggesting a possibility that at some point or other it may be completely filled with ore. How Measured. While the thickness of the ore body may be accurately measured at as many points as may be deemed desirable to get a fair average, the width of the vein (by which is meant the distance be- tween the walls at right angles to them, not horizon- tally) may be very difficult to ascertain, and many statements are made on this score with the best inten- tions, which are misleading, because the parties have no true idea as to what really constitutes the vein. Total Width and Ore Thickness. On the Comstock lode the distance between the east and west walls on the surface in the Savage mine was fully 1,000 ft., of which only a small part was quartz and of that only a portion was available ore. The width was about the same at the Chollar-Potasi mine, some 1,600 ft. to the 154 PROSPECTING AND VALUING MINES. south, with several quartz bodies cropping parallel to each other, of which pi. 2, fig. 2, will give a fair idea in cross section. These were at first supposed to be separate veins, but at about 330 ft. below the croppings the Savage mine was reduced to a width of 800 ft., nearly all waste matter; and the Chollar-Potasi mine to a width of 150 ft., all quartz, of which about one- quarter was ore. Veins on Dikes. In cases where the ore forms on the walls of a porphyry dike (as in many of the mines of the Monte Cristo district, in Washington), the prospector generally calls the entire dike the vein, giving it a width of from 20 to SO ft. or over, because he may be able to find traces of iron pyrite in the more decomposed portions of the dike, the bulk of which is, however, unaltered rock. Obviously the vein is only that portion of the decomposed dike which has been replaced by ore. To give the entire width of the dike as the vein, will create a very seri- ous misunderstanding,as it is scarcely probable that it will have been converted to an ore body for its full thickness, at any point of its length. False and Indistinct Walls. In other cases, where there has been much motion in the fissure, its walls may have become much shattered and rotten, forming a series of slabs, each of which may present the smooth face of a true wall, even to the slickensides, but which will peel off one after the other, after a short exposure to the air, making it difficult to state positively when the true wall is reached In slatey rocks there may be one wall well defined (if the vein is a contact) while parallel bodies of ore or barren ganglia may lie in the slates for several hun- dred feet from the contact (pi. 6, fig. 1), as in the mother lode of California. Under these circumstances it is better to give the width of the ore, and if there is a decided difference in its appearance, the width of each portion, taking samples as described in Chapter II. PROSPECTING, 155 If the length and width of the ore bodies as they show on the surface were ascertained in this manner, a large number of locations would be abandoned, having failed to stand the test of working value; and while the prospector would have fewer locations on his hands, he would be saved the burden of the annual assessment work on worthless properties, and he could .honestly ask capital to aid the development of those so carefully selected. 3. SAMPLES or THE COUNTRY EOCK. While a study of the chapter on rocks will have enabled even a beginner to speak of them with something like accu- racy, it would be well to take a small hand sample of the rock on each side of the vein. We have seen what important differences there are in the shape of deposits in different rocks, and one of the first questions an expert will ask is on this subject, as it affects also the cost of working most seriously, a drift or shaft in soft slate costing very much less than one in hard granite. Should there be a doubt as to the judgment or knowl- edge of the prospector the specimens will speak for themselves, and are nearly as important as the ore samples. These samples need not be taken immedi- ately from the walls themselves, as in such places the rocks are usually greatly decayed and unrecognizable in small pieces. It is better to take them a little dis- tance from the vein (say from the nearest outcrop in place), as these are likely to be solid, being harder than their neighbors, and while taking these samples to note whether the outcrop of the vein occurs in a country which is badly broken up, or whether the hills are large and smooth. The latter appearance promises better than the former for a solid continuous vein without displacements. In selecting specimens the prospector should also ascertain whether the vein runs parallel to the general direction of the rocks, or whether it cuts across the formation features which have an important influence on the probable perma- 156 PROSPECTING AND VALUING MINES. nence of the lode in depth, the latter structure almost necessarily involving a deep fissure of considerable length as well as depth. The names of even the common rocks seem to be a continual stumbling block to most prospectors, appar- ently for no other reason than a failure to realize the fact that each kind is made up of a definite combina- tion of a few minerals. It would seem as though the trouble of learning to distinguish from ten to twenty kinds, which is about all that is necessary, ought not to be such a serious matter. Every business has its own language, and those who wish to excel must necessarily learn to speak in a language which will convey the same idea to all hearers, and each word of which will convey a positive idea, instead of a hazy nothing. The writer recently met a prospector who had some fair-looking specimens of ore, but when questioned about the mode of occurrence and the lay of the country, in an effort to get an idea of the facili- ties for working, in reply to a question as to whether it was a granite country he answered "Yes." When asked if there was slate, "yes" was the reply. And to fully satisfj 7 any further inquiries which might be made for other rocks he added, "There is a regular jumble of them!" If this was really the case he had condemned his property, as such a condition neces- sarily involved a badly broken country, but it was evident that he knew nothing about the subject under discussion, while he simply cast a doubt upon every other statement he had made, showing that he was not a good observer. To make things worse he subse- quently inquired what basalt was worth, and when in- formed that it was merely a black volcanic rock with- out value for any of the precious metals, he gently intimated that his informant might know what he was talking about, but that he had his own opinion on the subject. His basalt proved to be orpiment, a yellow compound of arsenic and sulphur. PROSPECTING. 157 4. FACILITIES FOE WORKING. The faculty of locality, which must be well developed in a prospector to enable him to find his waj r through the wilderness, will usually also enable him to describe the best routes of access to his property and what can be done or has been done in the way of trails and roads. It will also enable him to answer questions as to the supply of timber for mining purposes (a most impor- tant item) and for fuel, if coal is not accessible, so that the water supply and the chances for economical development are the only questions to which we need allude in detail under this heading. If fuel is scarce and water abundant, the latter may furnish the motive power if the supply can be used under pressure, either directly or through the use of electricity, and to enable the prospector to readily estimate this power, a short chapter has been devoted to the measurement of water, and the method of calculating the horse power which a given quantity will develop. This depends on the quantity and the fall which can be secured, modified slightly by the distance it has to be taken to secure the fall, so that the prospector should be able to answer these questions approximately. A measure- ment of the supply taken in the dry season is most desirable as giving the supply which can be depended on all through the year without the use of reservoirs, which are costly and often impracticable. In not a few mining camps water is scarce during the early stages of development, but while this scarcity may increase the cost of the earlier work, the defect is one that usually remedies itself before any considerable depth has been attained, an abundant supply being generally secured from the shafts and tunnels, even if the quantity does not prove excessive as in Tombstone, Ariz., which in early days was a notoriously dry camp. The manner in which the vein can be opened to the best advantage will depend on the shape of the coun- 158 PROSPECTING AND VALUING MINES. try and the way the vein crosses it. If flat, shafts must bo resorted to; if hilly, it may be better to adopt tunnels if they can be run on the vein, and the pros- pector should inform himself thoroughly whether this can be done to advantage, which will depend on the position of the outcrop. This question is more fully treated in Chapter XII., on early development, and attention is merely called to it here, as one of the things on which all possible information should be acquired. 5. LESSON OF THE OUTCROP. All the foregoing remarks apply only to the surface observations, but in studying the outcrop we may gain some insight into the probabilities of depth. Present Appearance not the Original The first necessity is to disabuse the mind of the idea that the veins were all formed after the country had assumed very much its present shape and appearance. The remark so commonly made, that a vein which shows poorly on the surface will improve with depth, is based on this fallacy, the underlying idea evidently being, although probably not even thought out in the mind of the speaker, that the ore at that particular spot had not been able to reach the surface, a notion as- sisted by the other false idea that all the filling of the veins had been squeezed into them from below. As a matter of fact there has been an immense change in the surface since the majority of the min- eral deposits were formed. In the case of coal fields originally laid down horizontally and subsequently tilted to steep angles, whole sections of these fields have been worn away along with the inclosing rocks, or we should have no outcrop of them. In California we have absolute proof that the rocks which carry the gold veins have been worn away in places, even since the eruption of the basalt lavas which filled and cov- ered up the old river channels to a depth of fully 2,000 ft., as in the canons of Slate Creek, Canon Creek PHOSPECTING. 159 and others in Sierra and Plumas counties. As these old river channels carr.y gold, in fully as great a quan- tity as the modern placers, which must have been derived from the wear and tear of the hills which formed their flanks, there must have been extensive erosion before the flow of the lava, to carve out these immense valleys, so that we may add an unknown quantity to the known 2,000 ft., and probably be within limits if we estimate the degradation of the mountains carrying the gold veins at 4, 000 ft. or over. Writers on Abyssinia state that in the approach to Magdala gorges 4,000 ft. deep have been cut down through the basalt into the underlying rocks, leaving the basalt as table lands, much as in California, and if gold veins traversed the rocks of the Grand Canon of the Colorado we should have their secrets exposed 3,000 ft. below the top of the plateau, through which the river has carved its stupendous gorge. It is there- fore evident that in the great majority of cases the outcrops of veins may be called purely accidental ex- posures, which have been constantly changing in their appearance for thousands of years. Increase or Decrease in Depth. The erosion or wear and tear by air and water may have proceeded just far enough to uncover the top of the ore body, or it may have progressed so far that nearly all of it may have been removed. Are there any evidences in the outcrops themselves as to which stage has been reached? Before entering on this question, however, let us look at the probable increase or decrease in the value of the ore in depth. In the case of veins which carry large quantities of sulphuretted ores which are easily decomposed, such as iron and copper pyrites, we may expect a decrease in value on reaching the permanent water level of the mine, below which the decomposition will not have extended. If these iron pyrites carry gold, the gold will have been liberated by their decomposition, and 160 PROSPECTING AND VALUING MINES. will accumulate in the cavities of the rusty quartz; and as the ore after the removal of its sulphur and part of the iron is lighter, bulk for bulk, than the uudecomposed sulphides below, we have a greater bulk to the ton and also an enriched material, so that assays of the croppings are likely to be better than can be had after the water level is reached. In copper veins the decomposition of the copper pyrite results in the formation of the red and black oxides of copper (just as in the former case the product of decomposition was oxide of iron) both of which are richer in copper per ton than the sulphide; and as they are practically concentrated surface deposits, not extending below the water line, and may result from the decay and leaching of very poor ores, we have another instance in which the vein would be poorer in depth. But where no decomposition has taken place there is little or no proof of continuous improvement in depth, and more probability of impoverishment of the vein. If the former were the case the improvement ought to be continuous and there would be no limit to the increase of the deposit, which we know not to be the case ; and it is more than likely that the quality of ore varies greatly in nearly all instances, sometimes improving and sometimes growing poorer as the earth is penetrated, being governed very largely by changes in the character of the rocks traversed by the vein, and accidental conditions which we have not yet learned to realize and understand. But the prospector need be in no doubt on this point, as in most cases he can satisfy himself from personal examination as to the facts. If, as has been stated, the deposits were formed when the country was more elevated than at present, any ravine cutting across a vein or deposit explores it naturally as we do artificially by sinking a shaft, and if improvement fol- lows with increased depth, the outcrop at the bottom PROSPECTING. 161 of the ravine ought to be richer than one on the sum- mit, as a descent of 100 ft. vertically below the top of the ridge would be equal to the 100 ft. level of a shaft sunk on the outcrop 200 ft. would equal the 200 ft. level,and so on. How little this accords with experi- ence every prospector knows. Nothing but actual work can positively determine the question whether we have merely the top or the tail end of an ore body, as if we look upon the ore body as a roughly shaped lens, two parallel lines drawn through it, one just below the top and the other just above the bottom, would each cut off. a por- tion showing the same width and length; but if the ore is softer than the inclosing rock, and the vein crops in the bottom of a deep gorge, there is every probability that the gorge has been formed by the wearing down and removal of the ore body, that the outcrop found, if of small dimensions, is merely the lower end where the increased portion of country rock resisted the action of the stream to a larger extent and stopped further erosion. In a similar way, if the out- crop is on a steep hillside and of only limited length, it may in many cases indicate the termination of the ore body, as the erosion of the ravine which has ex- posed it has also disclosed some of the secrets of its penetration in depth, as just described in discussing the quality. But if the outcrop is of considerable length and thickness, this question need not trouble us, as there is sufficient justification for the expendi- ture of considerable money in development. The condition of the mineral in the outcrop may also furnish a slight guide as to probable permanence in depth. Some of the common minerals in ore, especially the several varieties of pyrite, are easily de- composed under exposure to air and water, and where there is evidence in the rustiness of the outcrop, or the presence of a spongy looking mass from which the crystals have been perfectly removed, we may cer- 162 PROSPECTING AND VALUING MINES. tainly infer that the drainage of the vein extends to some depth and involves a continuous fissure, as it is only by the presence of such conditions that the de- composition could have been effected. But if the pyrites remain in the croppings entirely undecom- posed, we may infer that the walls of the fissure are so tightly in contact below as to prevent the percolation or seepage of water downward, and this may be taken as an unfavorable sign. In soft and easily decomposed ore bodies the removal of the outcrop running along the face of a hill, instead of across it may result in shallow depres- sions, instead of a conspicuous ridge, in which the ore can only be found by digging; and when the ore is of this character, the search for it becomes a very laborious task, especially in moist and wooded coun- tries, where the vegetation may be exceedingly rank and tangled. Float. From what has been said of the origin of veins and the subsequent carving out of the ravines and valleys as they exist to-day, it is evident that there must be on the hillsides and in the ravines of a coun- try rich in minerals, many fragments of mineral detached from the ore bodies. These are called "float," and it is equally evident that the harder the material forming the gangue of the ore, the larger should be the number of fragments which have escaped the destructive action of air, frost, water and sun- shine. Such minerals as decompose very readily, or are excessively brittle, may disappear altogether, or nearly so, as coal or some forms of galena; but quartz- ose varieties may survive a long journey and be found at considerable distances from their original source. Large fragments indicate this source to be much nearer than small ones. Gravity has constantly car- ried these fragments to a level lower than their source, so that when tracing float, as so often done, we look for this source above the place at which the float has PROSPECTING. 163 been found. It may have reached this place either by rolling down the hillside in the immediate neighbor- hood, or it may have been carried down the bed of the ravine by water. The position of the float will gen- erally indicate which has been the method of trans- port, but in either case we must trace it upward, and if we find the fragments increasing both in number and in size, we may conclude that we are nearing the source of supply. Sometimes these may lead to the discovery of well-defined lodes, and again, in the case of quartz, we may finally lose all trace of it, without encountering anything of value. This is especially apt to be the case in slate countries, which have been crushed and crumpled and subsequently filled with innumerable thin- quartz seams. All the float may have been derived from these seams, and the float ceases because we have reached the limit of the slate formation, and enter a new series of rocks without quartz. This structure explains numbers of cases of "lost leads," but while there may be no well-defined vein or lode at the point where the ravine cuts the formation, if metal has been found in the float it shows that the region is worth prospecting and the search should be continued along the line of contact of the rock which has cut out the metal-bearing series. Topography and Water System. The reverse is just as likely to be the case where the ore body is soft, as nature always carves out a country on the lines of least resistance, which may be lines of faulting, or contact of a soft and a hard rock, or through soft ore bodies or between consolidated hard ones. For this reason the study of the water system of any particular mountain region affords a good insight into its phys- ical structure. If all rocks were of uniform and equal hardness, the face of a country would be planed down to uniform smooth slopes. It is the varying resist- ance of rocks which diversifies the mountain regions, in combination with the dislocations they have under- gone. 164 PROSPECTING AND VALUING MINES. GENERAL HINTS. What to Look for. The importance to the prospec- tor of knowing something about rocks becomes appar- ent. In a granite country it is evident that he may expect tin as well as a variety of other minerals, and should consequently know the ores of tin (and they often do not look like metallic ores) so as to be able to recognize them. In a limestone belt, galena, iron and zinc are specialities. In a country made up of vol- canic and eruptive rocks, it is useless to look for coal; but in such a country, where a belt of hot springs follow the junction of eruptive rocks, especially basalt, with a group of sedimentary strata, the ores of quick- silver should be in his mind. In a belt of hornblende rocks he may devote his energies to asbestos, soap- stone and chrome iron, as well as to the precious metals, and in sandstone and shale regions the out- look should be kept for coal, fire clays, iron, rock salt and gypsum. In a coal belt it is almost useless to expect mineral veins, for apparently no fissures made through a coal bed carry ore in the rocks above the coal, whatever they may do below. Any one who will take the trouble to put down the mineraroccurrences in any extended region will soon discover that they resolve themselves into a series of belts corresponding with the rock formation of the country, indicating most unmistakably the little understood relation be- tween them. In the large basaltic areas but little of interest or value need be expected, except such min- erals as opal, etc. ; nor is it any use to search for the soluble minerals, such as saltpeter, in any but exces- sively hot regions of depression, without drainage out- lets, and surrounded by volcanic or eruptive rocks. Where to Search. Above all things the prospec- tor's search should first be through all the accessible regions of a mineral country, for in such districts a much smaller ore body and a much lower grade of ore may be more valuable financially than greater size PROSPECTING. 165 and richness in less accessible localities amid moun- tain fastnesses and eternal snows. It is time to enter these when all others are exhausted, though their fas- cination is so extreme that it is to them that the hope- ful adventurer first directs his footsteps. Prime Requisites. What is wanted by the capi- talist is a large ore body, fair average quality, good working facilities and reasonably easy access. Given these, there is usually no difficulty in securing all the capital necessary. The want of any of these qualities in the mine renders the task more difficult. Outfit. The extent of equipment will vary accord- ing to the character of the country to be traversed, the distance from supply points, and whether the prospector has any means of conveyance, such as a pack horse or burro, or has to carry everything him- self. It is unnecessary to speak here of clothing, blankets, food, etc., further than to say that the lined and riveted canvas suits are perhaps the most service- able, and that comfortable as well as strong boots are an important item. Among the details of equipment the following may be mentioned. The horn spoon is preferable to the gold pan or. batea for prospecting, as being more con- venient to carry (it can go in a pocket) and in use requires very little water, and does not fatigue the user by causing prolonged stooping. A small bottle of quicksilver will be found useful when testing for gold in a very fine state. A compass with folding sights and a3-in. needle will help in laying off ground and connecting a location with other monuments or landmarks. A tape is not necessary, as one can be improvised from well stretched linen cord, standard- ized by some measure before starting and knotted at 1 ft., 1 yd., 10 yds. and 50 ft. long. If a regular tape is taken that with steel wire interwoven is preferable to a heavy steel tape, or a small self-winding narrow steel tape can be had, which occupies less than the space of a watch. A small bar magnet is useful in 166 PROSPECTING- AND VALUING MINES. cleaning up pannings. In this connection it may be noted that in the absence of a regular gold pan very good results can be obtained with almost any sort of a receptacle, such as a frying pan, tin dish, etc. For testing sulphurets and dark minerals generally a white surface is preferable, such as that of a sancer or small bowl, in using which when taking samples from a wet- crushing battery care must be taken to avoid overflow and consequent concentration if quantitative results are wanted. When sampling placer ground two buckets are very handy, to be used by washing from one to the other. To examine ores, float, pan or horn residues and rock minerals a lens is almost indispens- able, and the small powerful Coddington style is per- haps best. It can be hung to the watch guard. Every prospector ought to have some knowledge of the use of the blowpipe in determining ores and min- erals and making rough quantitative assays. The whole blowpipe kit necessary can go in the smallest size cigar box. The cheap black blowpipe answers as well as an expensive platinum-tipped one, and a tallow candle is for most purposes better than the alcohol or oil lamp. The half-dozen reagents suggest themselves. A small streak plate should be included in the kit. As to tools, the selection will depend upon means of carriage and whether any real opening work is intended. In prospecting in a bare, rocky counti'3 r where no digging is required, a light poll pick, with say a 3-lb. head or even lighter, is generally suffi- cient, as this tool combines pick with hammer. Regular geological hammers of peculiar shape and special steel can be bought or made by any good blacksmith, but are rather ornamental than necessary. Of course if there are two or more in the party each should take a different tool. If there is a pack animal, then a light working pick and small short- handled shovel will be taken. However, as to all these matters prospectors of any experience do not need to be told what is necessary, CHAPTER X. MAKING LOCATIONS, The object of making a location on a piece of min- eral ground is, in the first place, to give notice to all other persons that the locator has found mineral therein, and has made a claim to a definite portion of the deposit and a definite amount of ground to work it to the best advantage. To secure this object he posts on the mineral deposit a notice of his claim, to be filed for record with the proper authorities at a later date; and erects such monuments as will define the limits of the ground claimed. This notice and the monuments secure to the locator a possessory title, which is good so long as the requirements of the United States government, and the local laws of the particular mining district in which the claim is located, in regard to the amount of work to be done on the claim annually and other conditions, are complied with. The ultimate object of making a location is to secure a patent to the ground from the United States, if the property prove to be worth the expense. What is said here applied to the public domain of the United States, in the far West. In the Eastern States and in foreign countries the practice is differ- ent, and local regulations must be studied. The basis of all proceedings to acquire patent to mineral ground (see Chap. XI) is a duly certified copy of the notice of location and the monuments which it describes. 168 PROSPECTING AND VALUING MINES. Government Requirements. The instructions is- sued to the deputy mineral surveyors, to whom the work of making surveys for patent is intrusted, are of the most stringent character. "Under these instruc- tions, the surveyor has to report the true position of all the original monuments, or give good reason for their absence, which will be acceptable to the exami- ners of the United States land office at Washington; he must make the end lines of the claim parallel (if it be a lode claim); and he must not include within the exterior lines of the survey any ground outside the corner monuments. Whether this always does justice to the locator is not the question; it is the ruling of the department and must be respected. Neglect to restore monuments in the spring which may have been destroyed by winter storms, may result in litigation and endless delay in securing title, as their presence is the only thing which will debar a second party from coming on the ground and making an adverse loca- tion. It is taken for granted that a person making a location will look for monuments as a sign of previous appropriation of the ground, and their absence justi- fies the supposition that the ground is vacant and locatable, or if previously located has been abandoned by the earlier claimants. A locator cannot plead igno- rance of the absence of his monuments, because as they are the sole witnesses of the limits of his claim, and the essential means by which he holds possession, it is his duty as well as his interest to see that they are maintained in good order. Imperfect Locations. -- The number of locations which satisfactorily fill the requirements that is, which have all the monuments standing and so located that upon survey they will not exclude some portion of ground to which the claimant feels that he is honestly entitled, because the location was made and held in good faith is exceedingly small. The majority of original locations are very imperfectly made; not from MAKING LOCATIONS. 169 lack of good intentions on the part of the locator, but from want of knowledge as to what is required, or how to do it, or the lack of proper instruments. As at present interpreted, the instructions issued to the deputy surveyors really call for nearly as great accu- racy on the part of the prospector when making his location as they do from the deputy when making the final survey. Theoretically the regulations are based on the idea that in parting with the absolute title to the mineral lands (which until a comparatively recent period were regarded as the inalienable property of the crown) the government is doing so on such extraordinarily low and favorable terms that it has the right to demand from the recipient of its bounty what it considers to be nothing more than a very moderate expenditure of time and money in return for its liberality. If the original location has been carefully made, and the monuments equally carefully maintained, the appli- cant for patent will have no difficulties or delay in the land office proceedings, as 90% or over of all such troubles arise from defective locations or the absence of monuments which the government claims should be in existence. A large proportion of the remainder are dela3 r ed by the imperfect character of the work on which the right to patent is based. There seems to be a popular idea that it is within the scope of the authority of the deputy surveyor to restore such monuments as are missing, at the distance called for by the notice of location instead of in their original position, and not infrequently an implied feeling that he ought to do so because he had been favored by selection to do the work, and most deputy surveyors can testify to the difficulties which arise from this source, between the applicant for survey and the officers of the government, in which the deputy receives no support from the government and is very likely to secure the displeasure, if nothing more of the applicant. 170 PROSPECTING AND VALUING MINES. WHAT CAN BE LOCATED AND IN WHAT MANNER. - Knowing then what is required by the government, let us proceed to make a good valid location, or rather see what is necessary to make it good, first stating that the extra time necessary to convert a defective loca- tion into a good one is so small as to be of no conse- quence when compared with the subsequent saving of time, money, and annoyance; remembering that if the ground is worth locating at all it is worth while to make the location absolutely secure. Mineral Must be Found. No valid location can be made until mineral has been found within the limits of the claim in the condition required by the charac- ter of the location made. Placer locations may be made on ground in which valuable minerals, such as gold, tin, platinum, iridos- mine, etc., are mixed with sand, gravel, clay or bowl- ders, the minerals having been removed by natural causes from their original position in the rock in place. Placer ground on unsurveyed land may be taken in any shape which the locator desires, provided the ground contains mineral as described, and pro- vided the area does not exceed 20 acres to each locator or 160 acres to an incorporation. But if the land has been surveyed by the government, the claims must be made to conform to the smallest legal subdivisions (which in this case is 10 acres), the limits of the placer ground being first determined, and then so adjusted on the margins of the location that 10-acre tracts hav- ing less than five acres of placer ground are excluded, and those having more than five acres of available ground are included. When the final survey for patent is made on unsurveyed land, it will be made to conform to the original takes or monuments, no matter how irregular the shape of the track may be, regard- less of anything except area, and this, if in excess, must be cut down to the limit allowed by law. When the ordinary land surveys are extended over such MAKING LOCATIONS. 171 areas the section lines are adjusted to such surveys, just as in the case of lode claims. Lode Locations. In the location of mineral veins or lodes, whether they be of gold, silver, copper, lead, iron, tin, quicksilver or -other minerals found in lodes, the United States laws grant to each locator the right to take in one location not more than 1,500 ft. in length on the lode, and not more than 300 ft. on each side of the center of the lode. A location cannot be made with 200 ft. on one side and 400 ft. on the other. There is nothing compelling the locator to mats his location 600 ft. wide, the law simply says he may so make it. Local Regulations. Within these limits the width is optional with the locator, and by the action of a duly organized meeting of the miners in any district, may be limited to any quantity not less than 25 ft. on each side of the center of the lode, making a total width of only 50, instead of 600 ft. In Bodie, Cal., for instance, the width was fixed at 100 ft. on each side of the center line. The local laws of a mining district may impose any other conditions which the miners may see fit, pro- vided they do not grant better terms than are offered by the government. These may be just as much more stringent as the miners may think desirable for the welfare of the district, as, for instance, while the United States laws have been construed to grant the locator one year from the first day of January succeeding the date of his location in which to do the $100 worth of work by which he holds his title, the district laws may decide that work shall be commenced inside of 60 or any other number of days, or stipulate for other evi- dences of good faith on the part of the locator; but they cannot legally declare, as is sometimes attempted to be done, that a shaft 10 ft. deep, which only cost $50, shall be considered full value for the required annual expenditure of $100. Such a proposition is 172 PROSPECTING AND VALUING MINES. always open to contest. As the want of roads often greatly retards the opening of otherwise promising mining camps, a clause might very suitably be added to many local laws, stipulating that each location pay annually a definite sum to some authorized agent to accumulate as a road fund, in addition to the $100 work required by the government, but such payment could not be made to constitute a portion of the annual assessment work. Mineral "in Place." As previously stated, no loca- tion can be made which will be of any value until mineral has actually been found, and for a lode loca- tion it must be in the undisturbed rock, or "rc-^k in place." Monuments or no monuments, any outsider can prospect over such a lode location, and if h** suc- ceeds in finding mineral in place before the earlier claimant, he can make an adverse location ana will surely hold the ground. In Leadville, for instance, where the ore did not crop on the surface (u r ing nearly horizontally), the ground was covered with overlapping locations, but the shaft which first got down to and struck the deposit took the ground as against the other claimants. Agricultural and Timber Eights. No mining loca- tion, either lode or placer, or for iron or for coa-, can be made on any ground for which a patent has been issued, unless it can be conclusively proved thffc the party obtaining such patent was aware of the existence of mineral on his claim at the time of " proving up" and falsely swore to the contrary. This applies to patents to agricultural and timber lands. A lode claim can be filed over a placer claim, as lodes are expressly exempted from placer patents, but across such placer claim, the lode camp has surface ground only 25 ft. on each side of the center of the lode. Locations can be made on all other classes of land, provided mineral has been found thereon ; but when made on land valuable for timber or agricultural pur- MA KING LOG A TIONS. 173 poses, are liable to contests before the land office to determine whether the ground is more valuable for mineral or for other purposes. Monuments. A monument should be conspicuous enough to be readily found. According to the char- acter of the region, it may be either a tree with the side blazed; a small sapling cut off about 4 ft. from the ground with the top squared ; a simple stake about 4 ft. long squared at the top, and driven not less than 12 in. in the ground, if there are no rocks convenient; or such a stake with a rock mound at its base; or even a simple pile of rocks where there are no trees. Tree or Stake Marks. In all cases where a tree or stake is used a sufficient space should be smoothed on which to write the designation of the corner intended to be represented. If a tree is used, it is not suffi- cient to simply bark it, because trees in falling often skin the bark off each other in patches, and such a "blaze" is easily overlooked; but the blaze should be made as in pi. 15, figs. 1 and 2, with a straight notch at the bottom, cut well into the wood and dressed smooth to wrrte on with a soft pencil. Fig. 1 shows the front view of a proper blaze and fig. 2 the side ap- pearance. Such a mark is unmistakable and immedi- ately suggests the prior presence of men, which the other method does not. Stone and stake monuments are easily overturned and destroyed, especially in snowy altitudes and on steep hillsides, but there would not be half as much trouble in keeping them in good shape if a little more care were exercised in building them. They are usually a heap of rocks, instead of a monument. It takes no more rocks to build a good than a bad one, and but little if any more time all depends on the manner of placing the stones. If the monument is to contain a stake, this should be driven solid, with a rock for a hammer if necessary, and the ground roughly leveled off with the pick, which the prospector 174 PROSPECTING AND VALUING MINES, always carries, so as to get a good foundation. This is all important on a hillside. The necessary supply of rocks should then be got together, before starting the structure. The biggest and flattest should be laid in a circle round the stake, at a little distance from it, in such a way that their upper surfaces slope inward toward the stake. By taking this precaution with the bottom layer, the next layer will have a tendency to slide in toward the stake, thus making it almost im- possible for the monument to tumble down, while the stake will be wedged tightly in place by the pressure ; and if this principle is applied until the monument is completed, say three courses, with the inner space filled up solid with small rocks and dirt, there need be no fear of its destruction, except willfully or by snow- slides sweeping everything before them. If the latter are feared it is best not to have the central post too high, as it will then offer less resistance to the over- turning action of the snow. PI. 15, figs. 3 and 4, show a properly and an improperlj r built monument in cross section. In the latter there is every chance for the monument to fall apart and release the stake from its position. Every stone in a monument should be moved about until it has a perfectly solid bearing, and does not wobble. Simple Eock Monuments. In building a monument of rocks alone, the importance of a good foundation is even greater, for the absence of the central stake in- creases the liability to destruction. A moderately large base tapering somewhat rapidly will give the greatest stability. Inspection of Monuments. To emphasize the im- portance of building well, it will not be out of place to repeat that the owner of an unpatented claim should at least annually examine the corner monuments, and see that they are standing, for as they are often the only means by which a stranger can have knowledge of the existence of a location or its extent, and their MAKING LOCATIONS. 175 object, is to give notice to the world of an existing claim, their absence gives the stranger a perfect right to locate the ground as vacant lands of the United States. Notices of Location. These should accurately de- scribe the monuments as actually set. Prospectors frequently take out a set of printed blanks in which a "mound of stones" is usually called for, and then simply fill in the blank spaces with the number of feet located, when it often happens that no mound of stones was made, but a tree blazed, or a small sapling cut off, in places where there is a scarcity of rocks suita- ble for a monument. Frequently the stake called for does not exist, and the writer has seen cases where the monument, so called, was nothing more than a small piece of a broken limb stuck in the ground, without any notice of what it was intended to represent, and absolutely not recognizable as a monument, and this in the midst of dense timber. Such negligence is inexcusable, and if trouble arises the locator has no one but himself to blame. It is, of course, allowable to use one of these printed blanks to make and post the original notice at the point of discovery, to hold the claim while the discoverer may be putting up his end and corner monuments, but the final notice, of which a copy is filed for record, should call for a blazed tree, describing its markings, if such were used, a sapling squared, a post without mound, a post with rock mound, or a rock mound only, as the case may be. t Occasionally the notice of location calls for a monument of some kind, in a position which is inac- cessible, and where none was actually set, so that when the deputy surveyor comes along and reports that he cannot reach the point called for, there imme- diately arises a question of veracity between the loca- tor and the deputy, which may seriously delay the proceedings in the land office. If the point where the monument should be set is inaccessible, the location 176 PROSPECTING AND VALUING MINES. notice should say so, and give the reason for not set- ting the corner, and if set as a witness post to show the direction of the end line, the supposed distance to the corner should be written thereon. The absence of a post at any of the corners, if such cannot be set, does not invalidate a location, if the fact be so stated, as the law does not ask impossibilities, but the state- ment that a corner was set in an inaccessible place, when it was not so set, is sure to result in trouble. Posting Notices. In addition to fully describing the monuments in the notice of location, they should be so marked as to indicate what position they occupy with reference to the claim, as "north end center of Deadwood lode," "northwest corner of Dead wood lode" etc. ; but if a stone monument be used the notice may be folded up and placed between two flat stones or in a tin can, with the mouth downward to keep it dry. Such a tin can is also very useful even when a post is used, as it can be tacked to the same (pi. 15, fig. 5) in a similar manner and forms a very noticeable and conspicuous object. If there are trees near the monuments, they should also be blazed and marked as witness trees. The notice should distinctly state the name of the state, county and mining district in which it is made, the name of the miner, the name of the adjacent claims if they are known, the date of discovery, the date of location, with witnesses if possible, and refer- ence should be made to prominent natural objects, so as to make the position of the claim ascertainable, if, after all precautions have been taken, the monuments should be accidentally destroyed, as by floods or snowslides. Such references may be, for instance, "on south side of Index Mountain," "on the north side of Crab Creek, 2 miles above its junction with Pole Creek," "2 miles northeast of Minersville," etc. The exact wording of the notice of location is of but little consequence, so long as it gives the information MAKING LOCATIONS. 177 previously stated, as a location of lode claim neces- sarily carries with it all the dips, spurs and angles, and all the privileges granted by the various acts of Congress, without a recital of such claims. All that is required is such a document that no one can misun- derstand the intention of the locator. If this is clearly done, the shorter the notice the better. It has taken some time to describe the requisites of a first-class notice of location, whereas it only takes a few minutes to write it out and secure the satisfaction which always goes with a job well done, but it is not intended to imply that a notice not so complete as here sketched would be invalid. But very few con- tain every item in detail, yet the nearer it approaches to the correct thing the more safely can the prospector leave his claim to the tender mercies of the elements. How TO MAKE A LOCATION. Placer and Coal. In making a location of placer or coal ground on surveyed land the location notice should describe the ground by the usual legal subdivisions, and this will consti- tute a valid description because it can be immediately filed in the United States land office and become the best public notice obtainable; but if the placer claim is on unsurveyed land, a monument must be set at every change in the direction of the exterior bound- aries and mentioned in the location notice. Coal lands can only be taken in legal subdivisions as platted on the ordinary land surveys, and cannot be pur- chased before survey of the township has been made. Lodes. In the case of lode claims it is customary to set the ends of the lode line and the four corners of the claim, but there have been decisions by the gen- eral land office in which, with only the end center stakes established, the locations were sustained. If this method be employed the discovery stake, as well as the monuments at the ends of the claim, should be most thoroughly established, and all of them should plainly show that the locator claims a definitely speci- 178 PROSPECTING AND VALUING MINES. fied distance on each side of his lode line. Such de- cisions are based on the theory that the surface ground is granted only to enable the miner to work his claim to the best advantage, and on the further idea that a person finding a lode will naturally follow the outcrop in the course of his examination, and must consequently find any monuments already erected on the vein, thus gaining knowledge of the claims of any prior locators. But this would not occur if the locator were following a lode parallel to one previously located and say, therefrom, so that it is very much safer to establish all the corner monuments, this method having the additional advantage of defin- ing the direction of the end lines, which is left open to interpretation in the other case, unless it is plainly stated that they are to be at right angles to the lode line. The following remarks will therefore apply only to claims having all corners established, except where they are evidently applicable to other locations also. It may seem a very simple matter to make a lode location after finding ore just measure off 1,500 ft. and set the corner posts but there are many points to be considered, if we want to secure the full privi- leges granted by the mining laws. Should there be any mistake in the form or direction of the original location, and adjacent claims be taken either endwise or laterally before the mistake is discovered, it will be too late to remedy the defect by a new location; as, for instance; if the direction of the lode line as located does not follow the lode, which may be found to run diagonally across the location, and pass out of the side instead of the end lines. In such a case the side lines become the end lines, making the. location on the lode much shorter than if the lode ran lengthwise of the claim. To avoid such errors, which may ruin an otherwise valuable mine, time enough should be taken to ascertain the true direction of the vein before measuring off the location, After establishing the MAKING LOCATIONS. 1?9 initial monument or discovery stake on the ore body, and posting a notice of location thereon, so that there can be no doubt as to what vein is intended to be located, the prospector is entitled to a reasonable time in which to perfect his location. Very often the notice of location is posted at one end of the claim (see A 9 pi. 15, fig. 10) and calls for " 1,500 ft. on this vein, beginning at the post on which this notice is posted," or similar language, when there is no vein in sight at that particular point, leaving the intention of the locator uncertain, or to be interpreted only by finding the monument at the other end of the location, and ascertaining what outcrop may fall on a line drawn between the two monuments, which may or may not be the vein intended. As in pi. 15, fig. 11, if the notice be posted at either end of the lode line 1 or 2, a line connecting these points may show the outcrop of ore to be say 150 ft. from the line, in which case, in strict compliance with the law, in final survey for patent, the line from 5 to 6 should be run through the point 7, making the distance from 7 to the center of the outcrop not more than 300 ft. By establishing a discovery monument all doubt is ended. Lode Line and Outcrop. It is not absolutely neces- sary that the location should be made in a straight line, but the lode line should follow the outcrop with reasonable accuracy. This is often a very crooked line if the vein has a flat dip. If the vein is largely quartz and therefore generally harder than the sur- rounding country rock, it will probably crop boldly and can be traced without difficulty. If softer than the inclosing rocks, it may only crop on the steep sides of ravines, and be covered on the gentler slopes by earth and debris, in which case it may be necessary to dig a few cross trenches at short intervals apart, so as to disclose its course. (See Chap. IX., for method of tracing outcrop.) "When all other signs fail it will 180 PROSPECTING AND VAL UIN9 MINES. probably be found to run parallel to the general direc- tion of other veins in the district, or else nearly at right angles thereto. Jn the latter case it may prove to be only a spur of a larger vein, as shown on pi. 3, fig. 4, E. At any rate a notice at the point of discov- ery will hold a claim for a few days, while the true position of the end lines is being established, and with ordinary diligence and a little woodcraft the direction of the lode may generally be determined with a rea- sonable amount of accuracy, if the principles govern- ing the outcrop of a vein have been mastered, and the vein is strong enough to be worth locating. In cases where the vein does not crop distinctly for 1,500 ft., it will be good policy to make two locations, establishing one of the end lines of each location through the discovery stake on the outcrop as in p). 15, fig. 9, which leaves a portion of the cropping on each location, A and B. This plan has the advantage also of lessening the chance of the rake of the ore body in depth carrying it beyond the end lines of the claim, and offers a better chance to develop both locations through the same tunnel or shaft. This plan is much preferable to the common one (pi. 15, fig. 10) of cov- ering all the outcrop by the location A and making extension locations B and C, in which no outcrop is visible, as the latter locations are invalid until ore has been found in them. In the one case the locator has a good title to 3,000 ft. in the other to only 1,500. Length and Extensions. Having determined the direction of the lode line, and the manner in which he will make his locations, the locator can measure out any number of feet in either direction for his claim or claims, provided the total length of each one does not exceed the statutory limit of 1,500 ft., and the end monuments may be established. From the same point he can take one claim with say 500ft. in one direction and 1,000 ft. in the other, or two claims of 1,500 ft. each, one in each direction from the discovery. If MAKING LOCATIONS. 181 only one claim is laid off, it is good policy to be sure that the location is fully 1,500 ft. long; if a little more it will not matter, as on final survey the claim can be cut down to its proper length if in excess, but it cannot be lengthened beyond the original stakes, if they have been established too close together, and the claimant may lose a portion of ground to which he might have been legally entitled. If on the other hand, a series of locations are made on the same vein, it will always be policy to make the locations a trifle less than 1,500 ft. each in length (unless measured with the accuracy of a final survey), so as to avoid awkward gaps between them, as will be seen must occur in such a series as shown in pi. 15, fig. 6, where it is evident that the end lines of location A must be finally established at 1 and 2. If 2 has been taken as one end of B, the other must be set 20 ft. short of the original post at 3, or at 4. The ends of D can be set at 5 and 6, but if 5 be taken as one end of G there will be a gap of 60 ft. between 3 and 7, making a total of 80 ft. at this point to be relocated, and secured only by an expenditure of $500 for labor, in addition to the cost of survey and land office proceedings. Under other circumstances the gap of 20 ft. may occur near 2 and 60 ft. near 5. It is better to make the locations safe from this defect by making each of them a trifle short and making an additional one, if necessary to cover all the ground desired. Even in the case of four claims of rather irregular length, but aggregating just 6,000 ft., all owned by the same corporation, the laud office would not permit the adjustment cff the dividing end lines to make four even surveys of 1,500 ft. each, but requires strict adherence to the original monuments. Setting Corner Monuments. -In setting the corner monuments, be sure that they are> if anything, a little farther from the lode line than the distance called for in the notice of location, as the distance allowed on 182 PROSPECTING AND VALUING final survey cannot be greater than the position of the corner monuments calls for; in other words, the monuments govern and not the words of the location notice. No ground can be included in the final sur- vey for patent which lies outside straight lines con- necting the monuments as they exist on the ground^ and the end lines must be parallel. Having taken the precaution to keep the corner monuments far enough away from the lode line so that the finally established side lines shall fall within them, it is next necessary to see that they are so located that the end lines can be drawn parallel to each other, and yet pass through the end monuments on the lode line. It is here that the deputy surveyor usually encounters the greatest difficult}'. The situa- tion can best be explained by such a diagram as pi. 15, fig. 7, in which Z shows a defective location, be- cause if AB represents the lode line, and CJ),E,F, the four corner monuments; the surveyor, to make the end lines parallel, must prolong EB m toward F as in the dotted line, and then from C lay off a parallel line toward D thus cutting the lode line short by the dis- tance A H. He cannot draw the end line SS through A, because it would include ground outside the posts or monuments, namely the triangles S,D,A and S,C,A not included in the original location. In the same figure W shows a well-made location, so far as the prospector's interests are concerned, as it is evident that the end lines SS and 00 can be drawn through the lode line posts A and J", without shortening the length of the lode line, and can have a variety of di- rections given to them, while remaining parallel, a point of great importance, as will be seen shortly. It follows almost inevitably that one satisfactory loca- tion must in common practice necessitate an adjacent location in bad shape, so that whatever may be said of the policy of making the lode line monuments of one location common to its extensions, the ordinary prac- MAKING LOCATIONS. 183 tice of making the corner monuments also common to adjacent claims should be abandoned by those who wish to avoid trouble on final survey. Independent posts should be established as shown on pi. 15, fig. 8. In this figure the corner monuments of location A are marked a 3 a*a 5 a 6 , while its corners of location B are numbered 6 3 ,6*,fr 5 , and 6 6 . The diagram explains itself, being only two locations like W in fig. 7, placed end to end. By adopting this system, the parallel end lines can be located anywhere in the ground covered by the overlapping corners, as shown by the heavy parallel cross lines. End Lines. The acts of Congress grant to the locator 1,500 linear feet on the vein, and call for par- allel end lines, so that a uniform length on the vein shall be maintained at all depths, as the miners follow the vein downward on its dip, the end lines being ex- tended downward vertically and prolonged indefinitely in the direction of the dip. If any other policy were allowed, the ownership on the vein in depth would be a variable quantity, diminishing in length if the end lines of the claim converged toward each other in the direction of the dip, and increasing if they diverged from each other, as can bo seen by reference to pi. 15, fig. 12, which shows tw r o locations on the lode a b, the dip being indicated by the arrow. The dotted lines show the non-parallel end lines prolonged in the direction of the dip, and it is plain that the location G would constantly be gaining, while D would be losing ground in depth. For this reason the end lines of a claim must be kept parallel in justice to both locators. It is not, however, always an eas.y matter to do this, the first locator usually getting in practice an advantage over his later located neighbor. Surface Length and Actual Lode Length. While the grant says "1,500 ft. on the vein"it is in reality 1,500 ft. on the line of the outcrop of the vein measured horizontally, and by varying the angle between the 184 PROSPECTING AND VALUING MINES. end lines and the lode line, the locator may acquire either less than 1,500 ft. measured horizontally on the real vein or a great deal more. Take for instance the case presented in pi. 14, fig. 1, in which AB shows a location of 1,500 ft. on the outcrop of the vein AC, a tunnel on the vein starting on the outcrop at A and terminating at C, on the prolongation of the end line of the location DE, which is made at right angles to the lode line. The dip of the vein in the direction of the arrow is 60 from the horizontal, and the rise of the mountain side on which the outcrop is located from A to B is 500 ft. Fig. 2 shows a cross section of the lode on the line CDE in fig. 1, and the dimen- sions just given make the horizontal distance from BB, which is vertically under the point B on the out- crop on the end line, to the tunnel at C 287 ft. (ignor- ing fractions). Returning to fig. 1, the line AC, or the actual distance owned by the locator on the lode horizontal^, will therefore be longer than the length on the outcrop; viz., the square root of 1,500 squared plus 287 squared, or 1,527 ft. approximately. If the rise of the outcrop is 33, as is not infre- quent, the height of B above BBom C will be 817 ft. and the distance BC 408.5 ft. ; and AC will be 1,546.7 ft. But if the dip of the vein be 45 and the slope of the outcrop is 33, B will be 817 ft. above C; BC will be 817 ft. long, and AC 1,708.2 ft., or 208.2 ft. longer than the grant on the outcrop. Hence it can readily be seen that the apparently un- important question of the position of the end lines in really one of great importance to the owner, when the lode has a flat dip and crops on steep hillsides, cut- ting a smaller and smaller figure as the country be- comes flatter or the lode more vertical. "When per- fectly vertical both lines would be the same length; as also in a level plain. (PI. 14, fig. 1, is distorted to give better room for display.) MAKING LOCATIONS. 185 When making a single location on a vein, rect- angular end lines may be undoubtedly the best; but the reverse may be true where a series of such loca- tions are made, unless the outcrop of the vein follows a verj' straight line, which is only the case when it is nearly vertical. If sinuous or crooked, as in pi. 14, fig. 3, where a,aa"a" is the outcrop and the arrow shows the dip, a single location like ^will be satis- factory; but if we add another, as W, at a later date, ^will take everything in depth between the dotted lines ab and ab, while W will only be able to follow the vein downward till it encounters the line a'b, and stops the shaded triangle between the lines a'b and a"c. If a third location X be made as shown, no one will own the gore between the lines a'c and a"e, nor can title be acquired thereto, because there is no vacant ground on the outcrop at a" on which to base a location. This is, of course, an extreme case, but if all the locations are made in the interest of the same parties, it is evidently better that the end lines should be made as in pi. 14, fig. 4, because the distance on a horizontal line between the end lines ab and hh would always remain the same, at any depth; whereas in fig. 3 the end lines ab and a'"h converge, and would ulti- mately intersect each other and cut out the ownership of the lode completely. Puzzling Locations. It may be well to call atten- tion to some other defective forms which result from a vein with a dip, traversing a hilly country cut up with deep ravines, producing the results discussed in the subject of outcrops and illustrated in pi. 9, figs. 3 and 5, and from the frequent want of a continuous out- crop. If the ore chutes are as shown in pi. 9, fig. 7, the outcrops would be conspicuous on one side of the ravines as at cc, but would be scarcely visible on the other, as at dd. In a plan these outcrops would be seen as at aa in pi. 14, tig. 5, which shows two ravines with intervening hills. For want of knowledge how to 186 PROSPECTING AND VALUING MINES. trace a vein, a great number of locations are made by continuing the line of the visible outcrop as in the locations ZZ in a straight line, but if the dotted lines show the connecting portion of the vein, not exposed, it is evident that it will pass out of the side lines of the locations at bb. The complications which could arise from such a condition of things, on working the lodes, are almost endless, varying according; to the priority of location and the direction of the dip of the vein. Another form of trouble arising from the same causes is shown in pi. 14, fig. 6, in which aa are the outcrops of the same vein, on two sides of a ravine, the connection between the two not being visible on account of accumulated debris in the stream bottom. Instead of two locations crossing each other, a single location should have been made following the solid lines, but modifying the direction of the end lines as shown. Such a location, while having 1,500 ft. on the outcrop, would have a shorter length on the vein, but whatever this might be, it would remain uniform. In granite countries, especially, the ore bodies may be short, lying in the vein somewhat as shown in pi. 6, fig. 5, where the peculiarity is exaggerated for illustration, and may present themselves as a series of short, more or less parallel outcrops, as in pi. 14, fig. 7, aaa. These are often made the basis of a series of locations as XXX, when the true line of the vein is shown by the dotted line, and two locations, as ZZ, might have covered the property at a saving of several hundred dollars. CHAPTEE XL PATENTS TO MINING GROUND. IN the States and Territories where the United States mining law is operative the acquisition of title in fee simple to mineral land is somewhat more com- plicated than to agricultural lands, as special surveys must be made in most cases to separate it from the latter, except in the case of coal and stone lands, which are sold by subdivisions of the ordinary land surveys; or in the case of placer ground where the government surveys have already been extended over the placer area, in which latter case the land can only be taken iii the usual legal subdivisions, except that the selec- tion can be made in as small quantities as 10-acre tracts. But in all cases of application for patent to mineral land a full description by exterior boundaries, or by legal subdivisions, must be published, so as to allow an opportunity for agricultural claimants or others to contest the application, if so inclined. Except where special surveys have to be made to segregate the mineral land from the surrounding agricultural area, the proceedings originate in the "United States land office for the district in which the land may be situated ; but where surveys have to be made they originate in the office of the United States surveyor-general for the State in which the locations lies. Thus the United States surveyor-general deals only with those claims which require special surveys; and to these w ? e will first give attention, as they include the much larger proportion of mineral loca- tions. 188 PROSPECTING AND VALUING MINES. Before going further it will be well to note the dif- ference between a "location" and a "claim," as the words are often used indiscriminately, although in land office proceedings they have distinct and very differ- ent meanings. A lode location must not exceed 1,500 ft. in length by 600 ft. in width; and a placer loca- tion must not contain more than 20 acres, but may be of any shape necessary to cover the ground sought to be purchased. On the other hand a claim may include as many locations as the owner or claimant may have been able to purchase, provided they are adjacent to each other, and a patent for a single claim may con- tain many locations. In such a consolidated survey and patent the aggregate of say eight placer locations must not exceed 160 acres, and no one of the individ- ual locations must exceed 20 acres; if any of the loca- tions fall short of 20 acres, the loss cannot be made good by allowing an excess in some other location. Procedure on all Lode Locations, and such Placer Locations as Lie on Unsurveyed Land.' In these matters a uniform process must be gone through and a rigid adherence to the routine of the surveyor- general's office, as well as that of the local land office, will greatly facilitate progress. Duties of the Surveyor. All mineral surveys in- tended to form the basis of an application for a United States patent must be made by a deputy mineral sur- veyor. These deputies are appointed by the United States surveyor-general for the State, and are placed under bonds for $10,000, with two sureties, qualifying in double the amount, for the faithful performance of their duties, which are carefully defined in the gov- ernment instructions, and from which there can be no diviation without the risk of serious trouble both to the surveyor and the applicant. Deputy Surveyor's Fees. The deputy is paid for his services by the applicant, who has the right to select whomever he may prefer, and the compensation PATENTS TO MINING GROUND. 189 for the work is a matter of agreement between the applicant and the deputy, as there is no recognized scale of fees; such an arrangement being impossible on account of the widely different conditions under which the surveys are made as to accessibility of the locality, roughness of the ground and number of sur- veys to be made in any one locality. It is evident that the incidental traveling expenses will be just as great for the survey of one location as for ten, if they are in the same vicinity. The following extracts from the instructions issued to the deputy mineral surveyors by the surveyor- general for the State of "Washington will show the limit of their authority and furnish a guide to applicants for survey in preparing their case : Field Work (7). The survey made and reported must, in every case, be an actual survey of the ground in full detail, made by you in person after the receipt of the order, and without reference to any knowledge you may have previously acquired by reason of having made the location, survey or other- wise, and must show the actual facts existing at the time. If the season of the year, or any other cause, render such personal examination impossible, you will postpone the survey, and under no circumstances rely upon the statements or surveys of other parties, or upon a former examination by yourself. The term " survey " in these instructions applies not only to the usual field work, but also to the examinations required in the preparation of your affi- davits of $500 expenditure, descriptive reports on placer claims, and all other reports. (4) No return by you will be recognized as official unless made in pursuance of a special order from this office. Not to Act as Attorney (6). You are precluded from acting either directly or indirectly as attorney in mineral claims. Your duty in any particular case ceases when you have executed the survey and returned the field notes and preliminary plat with your report to the surveyor-general. You will not be allowed to prepare for the mining claimant the papers in support of his application for patent, or otherwise perform the duties of an attorney before the land office in connection with a mineral claim. You are not permitted to combine the duties of surveyor and notary public in the same case by ad- ministering oaths to parties in interest. In short, you must have absolutely nothing to do with the case except in your official capacity as surveyor. You will make no survey of a mineral claim in which you hold an interest. Survey and Location (8). The survey must be made in strict conformity with, or be embraced within, the lines of the recorded location upon which the order is based. If the surrey and location are identical, that fact must be clearly and distinctly stated in your field notes. If not identical, a bear- ing and distance must be given from each established corner of the survey to the corresponding corner of the location. The lines of the location as found upon the ground, must be laid down upon the preliminary plat in such a manner as to contrast and show their relation to the lines of the survey. (11) In accordance with the principle that courses and distances must give way when in conflict with fixed objects and monuments, you will not, under any circumstances, change the corners of the location for the purpose of 190 PROSPECTING AND VALUING MINES. making them conform to the description in the record. If the difference from the location be slight, it may be explained in the field notes, out if there should be a wide discrepancy, you will report the facts to this office and await further instructions. From the foregoing it will be seen how important it is that everything should be in good order on the ground before the surveyor is sent on to it. There is a widely prevalent idea that the surveyor can rectify any irregularities which he may discover, and reestab- lish corners which may be missing, without any prob- ability of future trouble, but this is not the case. It is true he can take testimony to ascertain the former position of missing corners, but this involves delay and extra expense for which, in the very large majority of cases, the applicants are unwilling to pay; and as the entire theory of the mining laws is based on the sup- position that a party places no value on a neglected article the applicant should not be surprised if the authorities who have to pass on the legality of his loca- tion take that view, and make no excuses for things which ought to have been, and might have been, in better shape. The duty of the surveyor is simply to report the facts as he finds them on the ground; if a stake or monument is missing he must so state, giving such reasons as may apparently account for its absence, at the same time leaving the examining authorities to judge whether such reasons are satisfactory; if the monument is in existence he must so report, and if not identical with the corner of a survey he must ex- plain why it is not; he cannot increase the length of a claim if it has been made less than 1,500 ft. originally ; and he must make the end lines parallel, though the side lines need not necessarily be so. In fact he is not allowed to be in any sense a judge of the equities of the case; he is simply employed to collect the in- formation by which others can adjust them. Duties of the Applicant. The following extract is from the official instructions; PATENTS TO MINING GROUND. 191 (4) ... You are therefore advised, before filing your application, to sec that your location has been made in compliance with law and regulations, and that it properly describes the claim for which patent is sought. Office Charges. There are certain charges for work in the office of the surveyor-general which are indepen- dent of the contract with the surveyor, and are intended to cover the cost of examining the filed notes of the survey and the preparation in quadruplicate of the maps and field-notes, one copy of which is sent to Washington to the general land office, two to the ap- plicant, and the other is retained on file in the office of the local surveyor-general.- (5) With regard to the platting of the claim and other office work in the surveyor-general's office, that officer will make an estimate of the cost thereof, which amount the claimant will deposit with any assistant United States treasurer, or designated depository, in favor of the United States treasurer, to be passed to the credit of the fund created by individual depos- tors for surveys of the public lands, and file with the surveyor-general the duplicate certificate of such deposit in the usual manner. (6) The following is the estimated cost of platting and other office work in connection with the survey of mineral claims :* Lode claim $35 00 Placer claim 35 00 Mill site claim 35 00 Mill site included in one survey with a lode claim 25 00 Each lode claim inc uded in the survey of a placer claim 25 00 Several lode or placer claims in one survey, each location , 35 00 Descriptive report on placer claim taken by legal subdivisions 10 00 (7) Should the office work, in any case, amount to more than the above estimate, an additional deposit will be required. (8) In districts where there is no United States depository, you should de- Eosit with the nearest assistant United States treasurer, or depository, and i all cases immediately forward the original certificate (of deposit) to the secretary of the treasury (at Washington, D. C.) and the duplicate to the surveyor-general, retaining the triplicate for your own use and security. Under no circumstances will the deposit be made w th the surveyor -general. The deposits for office work are not to be made until the applications for survey are received, and the parties notified by the survey or- general. The order of procedure is therefore as follows: 1. Application Blanks. As applications for survey must be made on the blank forms adopted by the sur- veyor-general's office, the applicant, unless he can secure one from the deputy surveyor, should write to the surveyor-general for a blank form. Particulars. This application contains the name of the deputy who has been selected to make the survey, *This is the scale issued by the State of Washington, and is only given tc convey a general idea of the cost. 192 PROSPECTING AND VALUING MINES. and a request for an estimate of the office fees. It should also be filled out with the name of the claimant in full, as it is desired to appear in the application to the land office for patent; the name of the mining claim in full, stating whether it is a lode or placer claim ; the name of the mining district, and the land office district in which the claim is located, and if the claim is made up of several locations, they should all be enumerated in detail. With this application, there must be forwarded in most instances, be made a salable or valuable proposition; and in a large proportion of cases, for want of judgment, the work done leaves the property looking worse than if nothing had been done upon it. Prospect Pits.- If only small sums of money are to be spent annually, these will be best expended in tracing the ore body by a series of shallow pits, rather than by starting short tunnels one after the other in places where work is easy, only to leave them in barren ground. As at present expended, most of the money spent on assessment work is prac- tically thrown away, for want of system. Large surface excavations, except such as are neces- 204 PROSPECTING AND VALUING MINES. sary to trace the ore, are not desirable, in wet or snowy countries especially, as they only serve to divert the rain and snow into the mine, from which it may later on have to be pumped at heavy cost. Common Terms Used in Mining.* Definitions of a few of these may be in place here: A "shaft" is a vertical opening, either on or alongside of the vein if that is vertical, or outside of it (preferably in the hanging country) if the lode has a dip, but intersecting it in depth. An "incline" is a sloping shaft, usually made to follow the vein or ore bed. It may not be so con- venient as a vertical shaft for working, but involves less dead work in opening a mine. A "winze" in a shaft connecting the interior workings, but not com- ing to daylight. It may be either vertical or an inclined winze. A "chute" (shoot) is a winze suitably lined to pass ore and waste from the workings to the cars on a lower level. ("Chute" is also applied to a pitching ore body.) The drain tunnel, or lowest horizontal opening by which water can be discharged from the mine, is the "adit." "Drifts" or "levels" run from the shaft from time to time as it is deepened; and are distinguished from "tunnels," which have one end open at the surface the distinction between a tunnel and a drift being the same as between a shaft and a winze. The face of the drift is called the "head" or "heading ;" ground from which ore is being taken between the different levels is called a "stope," and the ore may be removed either by digging down- ward, when the process is called "underhand sto- ping," or by working upward, in which case the operation is said to be "overhand" or "overhead." It is evident that by the latter method the material when broken down drops away from the workman more readily than by the former, and is usually the one em- ployed, unless circumstances absolutely prevent its economical adoption. The timbers which are put in to keep the walls apart after the extraction of the ore, EA RL Y DE VEL OP MEN T OF MINES. 205 and also to form working floors for the miners, are called "stulls," and the filling done with the waste material (in Cornwall Battle"), which is never taken from the mine, if possible to utilize it, is called the "gob. " When taken to the surface it forms the " waste dump." An excessively large dump of waste material indicates an excess of dead work in the mine; a small one on the other hand is by no means a bad gage of prosperity. The bottom of shafts, inclines and winzes into which the water of the mine drains, and in which the pumps are located, is known as the "smnp, " and is necessarily below the lowest working level, its depth being gaged according to the amount o^ water to be removed daily. CHAPTER XIII. ORES. DEFINITIONS. An "ore," strictly speaking, isasingle mineral which is a chemical compound of a useful metal and some other element or acid. In common usage, however, complex mixtures of pure minerals are considered arj single ores; while free gold, native silver and native copper, together with their accom- panying gangue minerals, are also classed as ore. Among miners whatever will pay to treat or ship and sell is considered ore, as also low-grade mineral which might be utilized by concentration or improved facili- ties; but there is an indefinite shading off into mate- rial containing traces of ore minerals but hopelessly unavailable, and this is not considered ore; neither are gold gravel or platinum sands called ore. To avoid misunderstanding, it is best to distinguish between the "ore" (meaning thereby the whole bulk of the available product) and the "ore mineral" (usually very much smaller in quantity in all ores except those of iron, manganese, and some lead and zinc ores). In this connection will be mentioned only those minerals which produce the bulk of the useful metals. Min- eralogists describe some 850 different mineral species, of which a considerable proportion might possibly be called ores; but only a comparatively few are of prac- tical importance the remainder are of interest only to the collector and scientist. It is believed thao those here described will be sufficient to enable the ORES. 207 prospector to recognize nearly all which are commer- cially valuable. The descriptions are based on those in Dana's "Min- eralogy," and are supposed to apply to the minerals in their pure, crystallized forms, but such items as hardness, weight, color and streak are common also to the massive forms. To make the descriptions short and compact a few terms and contractions are em- ployed, which need explanation : Adamantine, resembling a diamond. Amorphous, not crystallized; without any special form. Arborescent, resembling the growth of the branches of a tree. Botryoidal, made up of masses of varying size with smooth rounded surfaces, like grapes. Brilliant, applied to surfaces which are perfect reflectors of lighto Brittle, breaking easily. Compact, very close-grained, not showing special crystals. Conchoidal, as applied to surfaces of fracture, means resembling the inside of a clam' shell in shape. Concretionary, made up of particles which have apparently grown together into a solid mass. Ductile, capable of being drawn out into wire, or elongated. Flat, as applied to fracture, means smooth, like a board. Fibrous, like a bundle of threads laid side by side. Filiform, thread-like, not massed together as when fibrous. Foliated, made up of thin leaves like a book. Granular, made up of distinct grains like coarse sandstone. Iridescent, exhibiting a play of changeable rainbow colors. Malleable, flattening under the hammer without breaking. 208 PROSPECTING AND VALUING MINES. Mammillary, made up of many small rounded sur- faces like miniature breasts; usually applied to some forms of incrustations on rocks. Massive, not crystallized. Metallic, when descriptive of luster, means resem- bling polished steel, silver or other metals, as opposed to "earthy." Micaceous, made up of thin plates, resembling flakes of mica. Oolitic (o-o-litic), made up of rounded particles, like fish eggs. Opaque, will not permit the passage of light. Pisolitic, made up of rounded particles like peas. Eeniform, kidney-shaped. Resinous, resembling resin. Sectile, can be cut with a knife, like lead or easier. Shining, opposed to "earthy," when describing the "streak." Stalactitic, resembling the cylindrical masses found hanging from the roof of limestone caves, formed by dripping water. Subconchoidal, resembling conch oidal, but flatter, more like the inside of an oyster shell in form. Submetallic, with only a slight metallic luster, as a tarnished silver surface. Translucent, not perfectly clear, but resembling an egg when held up before a strong light. Transparent, permitting the perfect passage of light, like glass. Uneven, breaking into a rough face, like a broken brick. Vitreous, glassy. Waxy, as applied to luster, not quite so bright as resinous, resembling the surface of clean beeswax. It would not be possible to give a good idea of the forms assumed by the crystallized minerals without numerous diagrams, so that only occasional references are made to crystallization, The physical properties ORES. 209 used are the luster, color, streak, hardness, weight, and manner of breaking. By the "streak/' is meant the color of the scratch made by a penknife or the color of the powdered mineral. The weight is the specific gravity (in ratio to weight of equal bulk of water), indicated by the letter G, and is an important item in all concentrating operations or the sorting of ores. The hardness, indicated by the letter H, refers to a scale of hardness, in common use, in which crys- tallized varieties of the minerals mentioned are meant: 1, talc; 2, gypsum; 3, calcite or limespar; 4, fluor- spar; 5, apatite; 6, feldspar; 7, quartz; 8, topaz; 9, corundum; 10, diamond; so that if a mineral is said to have a hardness of 4 it would scratch 3, but would not scratch 5. GOLD Native. H. 2.53. G. 15.619.5. Yel- low, malleable, sectile. The depth of the yellow color varies with the amount of silver present in the metal, being deepest in the purest gold. When the value in silver becomes equal to the value of the gold, the native alloy is white. Distinguished from all minerals which it resembles, by flattening under the hammer, instead of breaking. The minerals for which it is most frequently mistaken are iron and copper pyrites, but it may be distinguished from these, when in such a position that it cannot be tested by the knife or hammer, by turning the specimen completely round in the sunlight, when it will be found to maintain the same color and appearance in every position. This is not the case with the other minerals mentioned, which will also float on the top of quicksilver, while gold will sink. Insoluble in simple acids. Distinguished from yellow mica by not splitting. Tellurides of Gold. These minerals are not found in large quantities, but are associated with other ores, and from their want of resemblance to gold often puzzle the prospector, who will get very large assays from samples which show no free gold. The four 210 PROSPECTING AND VALUING MINES. forms may be distinguished by the following char- acters. Three of them greatly resemble lead, and none of them are common enough to have local names. The important tellurides carrying gold are: Sylvanite.H. 1.52. G. 7.98.3. Luster me- tallic. Streak and color steel-gray to silver-white, sometimes brass-yellow. Fracture uneven. Approxi- mate composition: gold 30, silver 10, tellurium 60%. Nagyagite.H. 11.5. G. 6.87.2, Luster me- tallic, brilliant. Streak and color blackish lead-gray. Opaque. Sectile. Composition: 6 to 12% of gold with lead and tellurium. Petzite.R. 2.5. G. 8.89.4. Color between steel-gray and iron-black, sometimes tarnished with peacock tints. Streak iron-black. Brittle. Approxi- mate composition : gold 25, silver 41, tellurium 34%. Calaverite. Massive, without crystalline structure; color bronze-yellow; streak yellowish gray; brittle. Fracture uneven. Approximate composition: gold 41, silver 3, and tellurium 56%. SILVER Native. H. 2.53. G. 10.5. Luster metallic. Color and streak silver-white. Ductile. Tarnishes easily to grayish black. Malleable. Occurs as wire silver, crystallized (arborescent) or massive, up to 800 Ib. in weight. Argenlite, Silver Sulphide, Vitreous Silver, or Silver Glance. H. 22.5. G. 7.27.4. Luster metallic. Streak and color blackish lead-gray; streak shining. Opaque. Perfectly sectile. Occuis crystallized, amorphous, arborescent and filiform. Approximate composition; silver 85, sulphur 15%. Gives silver when heated on charcoal before the blowpipe. Pyrargyrite, Dark Ruby or Antimonial Ruby Silver. H. 22.5. G. 5.8. Luster metallic. Color black, sometimes approaching dark or purplish red. Streak cochineal-red. Translucent to opaque. Frac- ture conchoidal. Powder purplish red. Approxi- mate composition : silver 60, antimony 22, sulphur 18%. Decomposed by nitric acid. ORES. 211 Proustite, Light Red or Arsenical Ruby Silver.* H. 2 2.5. G. 5.5. Luster adamantine. Color cochi- neal-red. Streak cochineal-red sometimes brighter. Subtranslucent. Fracture conchoidal, uneven. Pow- der bright red. Approximate composition ; silver 65, arsenic 15, sulphur 20%. Decomposed by nitric acid. Freieslebenite or Gray Silver Ore. H. 2 2.5. G. 6 6.4. Luster metallic. Color and streak light steel-gray, inclining to silver-white, also blackish lead-gray. Yields easily to the knife, and is rather brittle. Fracture uneven. Powder steel-gray Ap- proximate composition ; silver 22, lead 30, antimony 28, sulphur 18, iron and copper 2%. Stephanite, Brittle or Black Silver. H. 22.5. G. 6.3. Luster metallic. Color, streak and powder iron-black. Fracture uneven. Approximate composi- tion; silver 68.5, antimony 15, sulphur 16.5%o Solu- ble in heated dilute nitric acid. Cerargyrite, Horn Silver or Chloride of Silver. H. 1 1.5. G. 5.5. When nearly pure, looks like wax. Luster resinous. Color pearl-gray, grayish green, whitish, rarely violet-blue, sometimes colorless when perfectly pure; brown, or violet-brown after exposure. Streak shining. Translucent. Sectile, cuts like wax. Not soluble in nitric acid. A fragment placed on a strip of zinc, and moistened with a drop of water, swells up, turns black and finally is entirely reduced to metallic silver, which shows the metallic luster on being pressed with the point of a knife. Composition : silver 75.3, chlorine 24.7%. Embolite or Bromide of Silver. H. 1 1.5. G. 5.5. Eesembles horn silver. Luster resinous. Color usually greener than horn silver, often dark, becom- ing darker on exposure. Composition : silver 67, chlorine 13, bromine 20%. (Besides the above, there are some 20 other silver minerals of small importance commercially.) PLATINUM Native. H. 44.5. G. 1619. Luster 212 PROSPECTING AND VALUING MINES. metallic, not very bright; color and streak -whitish steel-gray; shining. Opaque. Ductile. Malleable. Occurs usually in small grains; occasionally in masses of several pounds weight. Infusible. Soluble only in heated nitro-muriatic acid. IRIDOSMINE Native.' H. 6 7. G. 19 21. Lus- ter metallic. Color tin-white and light steel-gray. Opaque. Malleable with difficulty. Composition : the metals iridium and osmium in varying propor- tions, in combination with small amounts of rhodium, platinum and ruthenium. Occurs as small flattened grains in gold washings. QUICKSILVER OR MERCURY Native. G. 13.56. Fluid. Luster metallic. Color tin-white. Opaque. Cinnabar or Sulphide of Mercury. H. 2. G. 9.0. Luster adamantine, inclining to metallic when dark colored, and to dull in friable varieties. Color cochi- neal-red to brownish red and lead-gray. Streak scarlet; subtransparent to opaque. Fracture uneven. Powder bright scarlet, being the article known as ver- milion. Composition: quicksilver 86.2, sulphur 13.8%. Metacinnabarite. A dark to blackish variety of cinnabar. H. 2.5. G. 8.19. Luster metallic to dull. Color steel-gray or blackish lead-gray. Streak nearly black. Opaque. There are a number of combinations of mercury with selenium, chlorine and iodine which are of small commercial value. COPPER. All the following minerals marked with an asterisk (*) are dissolved in nitric acid, and will deposit red metallic copper on polished iron dipped into the solution. * Native. H. 2.53. G. 8.84. Luster metallic. Color copper-red. Streak metallic and shining. Ductile and malleable. * Chalcopyrite or Copper Pyrite. H. 3.5 4. G. 4.2. Luster metallic. Color brass-yellow; subject to ORES. 213 tarnish and often iridescent. Streak greenish black a little shining. Opaque. Fracture conchoidal, un- even. Powder greenish-black. Varies in the inten- sity of the yellow color, when massive, according to the amount of iron pyrite in the ore, becoming paler in proportion. It may be distinguished from iron pyrite also by being much softer and easily scratched with a knife. Composition when pure: copper 34, iron 30, sulphur 36%. *Cubanite, a Copper Pyrite. Similar to chalcopyrite. H. 4.0. G. 4.0. Cleavage rather more distinct than in ordinary pyrite. Massive. Color between bronze and brass-yellow. Streak dark reddish bronze to black. Composition; copper 21, iron 39, sulphur 39% with a little silica. *Barnhardite > a Copper Pyrite. Similar to chalco- pyrite. H. 3.5. G. 4.5. Compact, massive. Luster metallic. Color bronze-yellow. Streak grayish black, slightly shining. Fracture conchoidal, uneven. Brittle. Tarnishes easily to peacock tints, or becom- ing brown. Composition : copper 48, iron 22, sulphur 30%. *Bornite, Purple, Variegated, Horseflesh or Peacock Copper. H. 3.0. G. 4.5 5.5. Massive, structure granular or compact. Luster metallic. Color between copper-red and pinchbeck-brown; tarnishes easily to red, blue and purple tints. Streak and powder pale grayish black. Brittle. Easily scratched with a knife. Approximate composition : copper 58, iron 15 5 sulphur 27%. *Chalcocite or Vitreous Copper. H. 2.5 3.0. Go 5.6. Luster metallic. Color, streak and powder dark lead-gray ; often tarnishes blue or green. Streak sometimes shining. Resembles some silver ores, but gives copper instead of silver when heated on char- coal. Approximate composition : copper 78, iron 2, sulphur 20%. * Tetrahedrite or Gray Copper. H. 3,0- 4.5. G. PROSPECTING AND VALUING MINES. 4o5 5.L Luster metallic. Color between light flint-gray and iron-black. Streak and powder gen- erally the same, sometimes inclining to brown and cherry-red. Opaque. Bather brittle. Fracture sub- conchoidal, uneven. This is a very complex ore, carrying not infrequently a valuable amount of silver. Ordinary composition: copper 30 to 40; antimony 15 to 25; sulphur 20 to 25%; with iron, arsenic, zinc, silver, and sometimes mercury. In forty-seven analyses given by Dana, the silver contents range from a trace to 17%, and in one instance 31%, replacing copper or iron. * Cuprite or Red Oxide of Copper. H. 3.5 4.0. G. 5.8 6.0. Luster adamantine or submetallic to earthy. Color red of various shades, particularly cochineal- red ; occasionally crimson red by transmitted light. Streak and powder several shades of brownish red. Streak shining. Subtransparent to subtranslucent. Brittle. Fracture subconchoidal, uneven. Compo- sition when pure: copper 88.8, oxygen 11.2%. *Melaconite or Black Oxide of Copper. H. 3.0. G. 6 6.2. Usually massive or as an earthy powder. Luster metallic, and color steel or iron-gray when in thin scales; dull and earthy, with a black or grayish black color, and ordinarily soiling the fingers when massive or powdery. Composition: copper 79.85, oxygen 20.15%. * Malachite or Green Carbonate of Copper. H. 3.5 4. G. 3.74. Luster of crystals adamantine, inclin- ing to vitreous; of fibrous varieties, silky; often dull and earthy. Color bright green. Streak paler green. From translucent to opaque. Fracture subconchoidal, uneven. About 62% copper; remainder carbonic acid, oxygen and water. *Azurite or Blue Carbonate o f Copper. H. 3.5 4.2. G. 3.5 3.8. Crystallized or massive, also dull and earthy. Luster vitreous. Color various shades of azure blue passing into dark blue. Streak blue, ORES. . 215 lighter than the color. Fracture conchoidal. Brittle. Partially translucent when crystallized. About 61% copper, remainder carbonic acid, oxygen and water. Chrysocolla or Copper Silicate. H. 2.0 4.0. G. 2.1. Slightly crystalline; often opal-like or enamel- like in texture ; earthy. In seams or crusts. Some- times botryoidal. Luster vitreous, shining, earthy, Color green, bluish green passing into sky and tur- quoise-blue; brown to black when impure. Streak when pure, white. Translucent to opaque. Rather sectile; translucent varieties brittle. Eesembles the green carbonate, but is paler green, usually has a coarser texture (is never fibrous), a smoother surface, somewhat waxy luster, and is usually an incrustation upon other ores. About 35% copper; remainder silica, oxygen, water and small amount of iron oxide. Ata':amite or Chloride of Copper. H. 3.0 3.5. G. 3.7 4.3. Luster adamantine to vitreous. Color vari- ous shades of bright green, rather darker than emerald, sometimes blackish green. Streak apple-green. Somewhat translucent. Composition: about 58% copper; remainder oxygen, chlorine and water. Chalcocite, Sulphate of Copper, Bluestone. H. 2.5. G. 2.2. Crystallized. Luster vitreous. Color shades of blue from sky to darker; sometimes greenish blue. Streak uncolored. Taste metallic. Brittle. Sub- translucent. About 38% copper; remainder oxygen, sulphuric acid and water. Soluble in water. (In addition to the foregoing, there are of the rarer copper minerals some 21 combinations with sulr phur and arsenic; two with silica; 26 with phosphoric, arsenious or sulphuric acids; and tw 7 o other carbon- ates. They are, however, only mineral curiosities. The total number of copper-bearing minerals is about 65.) LEAD Native. H. 1.5. G. 11.44 when pure. Lus- ter metallic. Color lead-gray. Malleable and ductile. Galenite, Galena or Lead Sulphide. H. 2. 5, G, 216 PROSPECTING AND VALUING MINES. 7.2 7.7. Luster metallic. Color and streak lead- gray. Surface of crystals occasionally with bluish tarnisho Fracture flat, subconchoidal or even. Very brittle. Soluble in nitric acid. Yields lead or char- coal. Crystallizes in cubes. Composition : lead 86.6, sulphur 13.4%. The chief ore of lead; usually carries some silver, often some antimony. Cerussite or Lead Carbonate. H. 3.0 3.5. G. 5.4 6.4. Crystallized or earthy. Luster adamantine, inclining to vitreous or resinous; sometimes pearly; sometimes submetallic if the colors are dark or from superficial change. Color white, gray, grayish black, sometimes tinged blue or green by traces of copper. Streak uncolored. Fracture conchoidal; very brittle. Subtranslucent; usually opaque when massive. Be- sults from the alteration of galena, which often forms the core of massive varieties. Composition : lead about 70%, remainder oxygen, carbonic acid and impurities. Pyromorphite or Lead Phosphate. H. 3.5 4.0. G. 6.5 7.1; when containing lime 5.0 6.5. Luster resinous. Color green/yellow and brown, of differ- ent shades; sometimes wax-yellow and fine orange- yellow; also grayish white to milk-white. Streak white, sometimes yellowish. Subtranslucent. Brit- tle. Fracture subconchoidal, uneven. Occurs only with other ores. Composition : very variable, con- taining phosphates of lead and lime, chloride of lead, fluoride of lime and arsenic. Anglesite or Lead Sulphate. H. 2.753. G. 6.2, Luster highly adamantine, sometimes inclining to resinous and vitreous. Color white, tinged yellow, gray, green and sometimes blue. Streak uncolored. Transparent to opaque. Fracture conchoidal. Very brittle. Occurs massive, crystallized or stalactitic. Composition: lead, about 64%; remainder oxygen and sulphuric acid. Easily fusible. Massicot or Lead Oxide, H. 2.0* GK 8,09,0, ORES. 217 Luster dull. Color between sulphur and orange- yellow, sometimes reddish. Opaque. Massive or earthy. Composition: lead 92.83, oxygen 7.17. Minium or Red Oxide of Lead. H. 2.0 3.0. G. 4.6. Powdery. Luster dull or slightly greasy. Color bright red, mixed with yellow ; streak orange- yellow, Opaque. Composition: lead 90.66, oxygen 9.34%. These oxides do not yield much commercial lead, but are given as they often occur as powdery matter in the so-called "chloride" ores of the miners. (Besides the above there are some 40 non-cornmer- cial lead minerals, in which lead is combined with sulphur, antimony, chlorine and oxygen ; or with ar- senious, antirnonious, phosphoric, tungstic, molybdic, vanadic, sulphuric, chromic, selenious and carbonic acids. Several of these, such as the molybdate of lead (wult'enite) and the vanadate of lead, are beau- tiful waxy minerals of various shades of color from lemon-yellow to red, occurring usuall3 r in crystallized forms, making beautiful cabinet specimens but not otherwise specially valuable). ZINC Smithsonite, Drybone or Zinc Carbonate. H. 5.0. G. 4 4.4. Occurs crystallized, reniform, botry- oidal or stalactitic and as incrustations; also granular and sometimes earthy and powdery. Luster vitreous, inclining to pearly. Color white, often grayish, greenish, brownish white, sometimes green and brown. Streak white. Brittle, Fracture uneven. Approxi- mate composition : zinc 52%, remainder oxygen and carbonic acid. Usually carries small quantities of lead and iron. Calamine or Zinc Silicate. H. 4.5 5.0. G. 3.5. Occurs crystallized, stalactitic, botryoidal and fibrous; also massive and granular. Luster vitreous. Color white, sometimes with -a delicate blueish or greenish shade; also yellowish to brown. Streak white. Fracture uneven. Brittle. Contains 67.5% oxide of zinc. 218 PROSPECTING AND VALUING MINES. (The last two minerals are very much alike in their general appearance, but smithsonite is soluble in muriatic acid, while calami tie forms a gelatinous mass under the same conditions, and is soluble in strong caustic potash.) Zincite or Red Zinc Oxide. R. 4.04.5. G. 5.6 Usually in foliated grains, or coarse particles and masses; also granular. Luster subadamantiue. Color orange-yellow to deep red. Streak orange-yellow. Brittle. Fracture uneven. Subtransluceut. Com- position: zinc 80.26, oxygen 19.74%, usually contain- ing small quantities of manganese. Blende, Zincblende, Zinc Sulphide or Blackjack. H. 3.54.0. G. 3.94.2. Luster resinous to adamantine. Color brown, yellow, black, red, green; wlaite or yellow when pure. Streak white to reddish brown. Powder nearly white, even in dark varieties. Fracture conchoidal. Brittle. Translucent to opaque. Crystallized or massive. Composition: zinc 67, sulphur 33%. Distinctly clearable. Franklinite.lA. 5.56.5. G. 5.60. Crystallized and massive, either granular or compact. Luster metallic. Color iron-black. Streak dark reddish brown e Opaque. Brittle. Fracture conchoidal. Acts slightly on the magnet. Soluble in muriatic acid. Approximate composition : zinc oxide 18, manganese oxide 16, iron oxide 66%, the proportions of zinc and manganese varying considerably. Willemite, a Zinc Silicate. H. 5.5. G. 4.0. Crys- tallized massive or in grains; sometimes fibrous. Luster resinous. Color whitish or greenish yellow when purest; apple-green, flesh-red, grayish white, yellowish brown ; often dark brown when impure. Streak uncolored. Transparent to opaque. Brittle. About 58% zinc; remainder oxygen and silica. Car- ries small quantities of iron and manganese. (Besides the above there are some 15 other zinc- bearing minerals of minor importance.) ORES. IRON Magnetite or Magnetic Iron Ore. H. 5.5 6.5, G. 5.18. Luster metallic to subrnetallic. Color and streak iron-black. Opaque. Fracture subcon.- choidal, shining. Brittle. Strongly magnetic, sometimes possessing polarity, like the needle of a compass. Composition: iron 72.4, oxygen 27.6%. Hematite or lied Oxide of Iron, or Specular Iron Ore. H. 5.5 6.5. G. 4.2 5.3. Crystallized, colum- nar, granular, botryoidal and stalactitic, as well as micaceous and compact. Luster of crystals me- tallic, sometimes brilliantly so; sometimes earthy. Color dark steel-gray or iron-black ; when earthy inclined to red. Streak cherry-red or reddish brown. Opaque. Fracture subconchoidal, uneven; some- times slaty. Sometimes attractable by the magnet. Composition : iron 70, oxygen 30%. Varies consid- erably in its mode of occurrence and outward appear- ance. When excessively lustrous and brilliant it is known as "specular iron ore;" when in .thin flakes and foliated, "micaceous iron ore;" when compact or fibrous with a reddish brown or iron-black color, "red hematite;" or "clay iron ore" when mixed with earthy impurities, and possessing an earthy appear- ance and no luster, with not infrequently a deep dull red color. Limonite, Brown Hematite or Bog Iron Ore. H, 5.0 5.5. G. 3.6 4.0. Usually in stalactitic and botryoidal forms, having a more or less fibrous struc- ture; also concretionary, massive and occasionally earthy. Luster silky, often submetallic; sometimes dull and earthy. Color of surface of fracture various shades of brown, commonly dark, and none bright; sometimes with a nearly black varnish-like exterior; when earthy, brownish yellow to yellow ocher. Streak yellowish brown. Composition : differs from hematite in carrying about 16% of water. The term "bog" ore is applied to the modern formations found in marshy places, which usually conteJu manganese as an impurity. 220 PROSPECTING AND VALUING MINE8. (The three foregoing minerals produce the bulk of the iron of commerce. They can readily be distin- guished from each other by the streak, which is respectively black, red or yellowish brown. The following minerals, while strictly iron ores, are valu- able chiefly for their other constituents such as zinc, chrome, sulphur, arsenic, etc., and the precious metals found in their company.) Franklinite. Described with the zinc minerals. Sidemte, Spathic Iron or Iron Carbonate. H. 3.5 4.5. G. 3.8. Occurs crystallized; also in botryoidal and globular forms, somewhat fibrous within, occa- sionally silky. Often massive. Luster vitreous, more or less pearly. Color ash-gray, greenish gray, also brown and reddish brown, rarely green; sometimes white. Fracture uneven. Brittle. Streak white. Composition: oxide of iron 62.1, carbonic acid 37.9%. 'Usually carries manganese, magnesia and lime as impurities. A sparry looking ore, distinctly cleavable, turning brown to black on exposure. A good ore of iron when abundant. Pyrite, Iron Pyrite or Iron Sulphide. H. 6.0 6.5. G. 4.8 5.2. Crystallized or massive. Luster metallic, splendent to glistening. Color a pale brass-yellow nearly uniform. Streak greenish or brownish black. Opaque. Fracture conchoidal, uneven. Brittle. Strikes fire with steel. Composi- tion (omitting impurities): iron 46.7, sulphur 53.3%. Crystallizes in cubes. The pyrites of gold regions usually carry gold, which may be occasionally seen projecting from the faces of the crystals. Other varieties carry small quantities of nickel, cobalt, silver or tin. Pyrite is one of the commonest of minerals, and aside from the precious metals it contains, is chiefly used in the manufacture of sulphuric acid, the acid being produced more cheaply by this method than from sulphur direct. -' Similar to ordinary pyrite in composi- ORES, 221 tion, but differs in the form of the crystals, which are often flat and crested. H. 6.06.5. G. 4.8. Crys- tallized, globular or reniform ; often massive or gran- ular. Luster metallic. Color pale bronze-yellow, sometimes inclined to green or gray. Streak grayish or brownish black. Fracture uneven. Brittle. Often carries gold. Pyrrhotite or Magnetic Iron Pyrite. H. 3.5 4.5. G. 4.6. Commonly massive or granular. Luster metallic. Color between bronze-yellow and copper- red, and tarnishing easily. Streak dark grayish black. Brittle. Magnetic, being attracted in fine powder by a magnet, when not affecting a magnetic needle. This ore is valuable chiefly for the nickel it contains, which in some cases ranges from 3 to 5%, and furnishes the bulk of the nickel of commerce. Composition: iron 60.5, sulphur 39. 5%. Mispickel or Arsenical Parties. H. 5.5 6.0. G. 6.0 6.4. Luster metallic. Color silver-white, in- clining to steel-gray. Streak dark grayish black. Fracture uneven. Brittle. Composition: iron 34.4, sulphur 19.6, arsenic 46.0%. This mineral is the source of the bulk of the arsenic of commerce, as well as cobalt, and is associated with and frequently carries silver and gold in small quantities. llmentie or Titanic Iron. H. 5.06.0. G. 4.5- 5.0. Massive or as loose grains in sand. Luster submetallic. Color iron-black. Streak submetallic, powder black to brownish red. Opaque. Fracture conchoidal. Slightly influencing the magnetic needle. Composition : oxide of iron with varying amounts of titanium, 3 to 30%. Not a true iron ore. (Besides the above there are nearly 40 other non- commercial iron minerals, consisting of silicates, sul- phates, phosphates, arsenates, carbonates, etc.) MANGANESE Manganite. H. 4.0. G. 4.3. Occurs crystallized, stalactitic, seldom granular. Luster sub- metallic. Color dark steel-gray to iron-black. Streak 222 PROSPECTING AND VALUING MINES. and powder reddish brown, sometimes nearly black. Opaque. Fracture uneven. Composition: manganese 62.5, oxygen 27.3, water 10.2%. Pyrolusite, Manganese Dioxide. H. 2.0 2.5. G. 4.8, Luster metallic. Color iron-black, dark steel- gray, sometimes bluish. Streak black or bluish black, sometimes submetallic. Opaque. Bather brit- tle. Composition: manganese 63.3, oxygen 36.7%. One of the most important ores of manganese; it is easily distinguished from psilomelane by its inferior hardness, and being usually crystalline; from rnan- ganite, by the color of the streak and powder. Often soils the hands. Psilomelane or Black Manganese Oxide. H. 5.0 6.0. G. 3.7 4.7. Occurs massive and botryoidal s reniform and stalactitic. Luster submetallic. Color iron- black, passing into dark steel-gray. Streak brownish black, shining. Opaque. Composition : an oxide of manganese (variable in quantity) with oxide of bar- ium, and several other impurities in minor quantities. Not being found crystallized the exact nature of the species is yet doubtful. Wad or Bog Manganese. The ores included under this name occur in amorphous and reniform masses, either earthy or compact, and sometimes incrusting. They are mixtures of different oxides and cannot be considered a distinct species. H. 0.5 6.0. G. 3.0 4.2, often loosely aggregated and feeling very light to the hand. Color dull black, bluish or brownish black. Composition: manganese oxide, with iron, barium, cobalt and copper oxides in varying propor- tions. (There are, in addition to the above, some 20 other unimportant manganese minerals.) TixCassiterite or Tin Oxide. H. 6.07.0. G. 6.4 7.1. Occurs crystallized and massive. Luster adamantine, and crystals usually splendent. Brown or black; sometimes rod, gray, white or yellow. ORES.. 223 Streak white, grayish, brownish. Crystals nearlj r transparent, sometimes opaque when massive. Frac- ture subconchoidal, uneven. Brittle. Composition : tin 78.67, oxygen 21.33%'. Furnishes the tin of com- merce. Does not look much like a metallic ore and is often confounded with the valueless mineral epidote. Only slightly acted on by acids. Detected usually by its weight. Stream tin is nothing but the ore in the state of sand, as it occurs in the gravel derived from the decomposition of the rocks carrying the ore. Wood tin is an irony-looking mineral, a variety of cassiterite, very heavy, occurring in rounded, botry- oidal or reniform shapes, concentric in structure, and radiated fibrous internally, although very compact, with the color brownish, and the rings of mixed shades, looking somewhat like dry wood. Occurs in the gravel of streams. Stannite or Tin Sulphide. H. 4. G. 4.4. Com- monly massive, granulated, or disseminated through the rock in small grains. Luster metallic. Color steel-gray to iron-black, the former when pure. Streak blackish. When copper pyrite is present in the ore the color is often yellowish. Opaque. Brittle. Frac- ture uneven. Composition: tin 27.2, copper 29.3, sulphur 29.6, iron 6.5, zinc 7.5%. It frequently has the appearance of bronze or bell metal, and is hence called "bell metal" ore. (Tin is found in small quantities as a component of several other ores.) CHROMIUM (Jhromite or Chrome Iron. H. 5.5. G. 4.4. Usually occurs massive; structure fine gran- ular or compact. Luster submetallic. Streak brown. Color between iron-black and brownish black. Opaque. Brittle. Fracture uneven. Sometimes magnetic. Composition: oxide of chromium 68, oxide of iron 32%. Usually with alumina and silica as impurities when massive. The ore has usually green incrusta- PROSPECTING AND VALUING MINES. tions in the seams which distinguish it readily from the other iron ores. Affords the chrome of commerce, not being used as an iron ore. (Several other ores contain chromium, but not in available quantities.) NICKEL Pyrrhotite or Magnetic Iron Pyrite. (See iron ores). The chief source of nickel. Niccolite, Copper-nickel or Arsenical Nickel. - Usually massive, no visible structure; also reniform and arborescent. H. 5.0 5.5. G. 7.5. Luster me- tallic. Color pale copper-red, with a gray to blackish tarnish. Streak pale brownish black. Opaque. Brittle. Composition: nickel 44.1, arsenic 55.9%; sometimes part of the arsenic is replaced by antimony, with small quantities of lead, cobalt and sulphur. Kesembles pyrrhotite or magnetic iron pyrite, but is not magnetic. Gersdorffite or Nickel Glance C rystallization cubic; also lamellar and granular massive, H. 5.5. G. 5.6 6.9. Luster metallic. Color silver-white to steel-gray, often tarnished gray or grayish black. Streak grayish black. Fracture uneven. Composi- tion : nickel 35.1, arsenic 45.5, sulphur 19.4%, with part of the nickel often replaced with iron or cobalt. Out of 18 analyses the nickel ranges from 19 to 40%. Gent/lite or Silicate of Nickel. Not crystallized, occurring usually as incrustations. H. 3.4. G. 2.4. Luster resinous. Color pale apple-green or yellowish* Streak greenish white. Translucent to opaque. An unimportant compound of nickel and silica, often associated with chrome iron. Annabergite or Nickel Ocher. In slender crystals; also massive and disseminated through the gangue. Soft. Color fine apple-green. Streak greenish white. Fracture uneven or earthy. A compound of nickel and arsenic. Unimportant. Zaratite or Emerald Nickel. Incrusting, also mas- sive and coraDact. H. 3,0 3.2. G, 2.6. Lustfv: ORES. 225 vitreous. Colo* 1 emerald-green. Streak pale green. Translucent. Brittle. A carbonate of nickel. Unim- portant. (The last three minerals, with several others of similar green color, include the green minerals found in nickel ores, and which usually attract the attention of the prospector from their bright color, resembling the green carbonate of copper.) COBALT Mispickel or Arsenical Pyrite. (Described under iron ores). ISmaltite, Smaltine or Cobalt Arsenide. Crystallized and massive. H. 5.56.0. G. 6.4 7.2. Luster metallic. Color tin-white, inclining when massive to steel-gray, sometimes iridescent or tarnished. Streak grayish black. .Fracture granular and uneven. Brittle. Composition: cobalt 9.4, nickel 9.5, iron 9, and arsenic 72.1%. In some varieties the nickel is absent and the cobalt runs up to 23% or over, replac- ing the nickel and part of the iron. Gobaiiite, Cobaltine or Cobalt Glance. Crystallized, massive, granular and compact. H. 5.5. G. 6.0 6.3. Luster metallic. Color silver-white, inclined to red; also steel-gray with a violet tinge, or grayish black when containing much iron. Streak grayish black. Fracture uneven and lamellar. Brittle. Com- position : cobalt 35.5, arsenic 45.2, sulphur 19.3%. The cobalt is sometimes largely replaced by the iron, in which case the percentage may run down as low as Erythrite, Cobalt Bloom or Red Cobalt. Crystal- lized, also in globular and reniform shapes; also as incrustations and powdery. H. 1.5 2.5. G. 2.9. Luster pearly to vitreous; also dull and earthy. Color crimson and peach-red, sometimes pearl to greenish gray; red tints incline to blue. Streak a little paler than the color; the dry powder deep lavender-blue. Subtranslucent. Sectile. Composi- tion: oxide of cobalt 37.55, arsenic acid 38.43, and 226 PROSPECTING AND VALUING MINES. water 24.02 %. The delicate peach-red of this min- eral is very characteristic. (The above are the chief cobalt ores. There are a few others of less importance. Cobalt is a frequent associate in nickel ores, and both nickel and cobalt often occur in copper ores.) ANTIMONY Stibnite, Antimony Sulphide, Gray Anti- mony or Antimony Glance. Occurs crystallized or mas- sive. When massive, not infrequently more or less fibrous or radiated. H. 2.0. G. 4.5. Luster metal- lic. Color and streak lead-gray, inclining to steel- gray; liable to blackish tarnish. Fracture small sub- conchoidaL Sectile. Composition: antimony 71.8, sulphur 28,2%. Eesemblessorne manganese ores, but is distinguished by being easily fusible. Furnishes the bulk of the antimony of commerce. (Native antimony and the oxides do not occur in quantities to make them valuable as ores of the metal. ) ARSENIC Realgar or Red Sulphide of Arsenic. Crystallized or granular and compact. H. 1.5 2.0. G. 3,5. Luster resinous. Color aurora-red or orange- yellow. Streak similar. Translucent. Fracture un- even. Composition: arsenic 70.1, sulphur 29.9%. Orpimentor Yellow Sulphide of Arsenic. Crystallized or massive. H. 1.5. G. 3.5. Luster pearly on the faces of cleavage, elsewhere resinous. Color several shades of lemon-yellow. Streak a little paler than the color. Subtranslucent. Subsectile. Composition : arsenic 61, sulphur 39%. (The above minerals do not occur in large quanti- ties. Artificially-made orpiment is used as a paint. Commercial arsenic is usually a by-product from the working of mispickel and the ores of nickel and cobalt.) BISMUTH Native. Crystallized, foliated or gran- ular. H. 2.0.-- 2.5. G. 9.7. Luster metallic. Streak and color silver-white, with a reddish hue; subject to tarnish. Opaque. Sectile. Brittle when ORES. cold, but somewhat malleable when heated. Very fusible. (Bismuth occurs in some dozen combinations, but usually in small quantities with other compounds in mineral veins. The native metal furnishes the bulk o.f the commercial article.) TITANIUM Entile or Titanium Oxide. Crystallized or massive. H. 6.0 6.5. G. 4.2. Luster metallic- adamantine. Color reddish brown, passing into red ; sometimes yellowish, bluish, violet, black; rarely grass-green. Streak pale brown. Subtransparent to opaque. Fracture subconchoidal, uneven. Brittle. Composition : titanium 61, oxygen 39%. (Ilmenite, titanic iron, etc., are described with the iron ores.) TUNGSTEN Wolframite, Tung state of Iron. Crystal- lized or massive. H. 5.0 5.5. G. 7.1 7.5. Lustersub- raetallic. Color dark grayish or brownish black. Streak dark reddish brown to black. Opaque. Com- position : tungstic acid 76%, in combination with iron and manganese in variable quantities. (The tungstates of lead and lime are of minor im- portance.) CADMIUM Greenockite or Cadmium Sulphide. H. 3.0 3.5. G. 4.8. Luster adamantine. Color honey-yellow, citron-yellow, orange-yellow, bronze- yellow. Streak and powder between orange-yellow and brick-red. Nearly transparent. Composition : cadmium 77.7, sulphur 22.3%. MOLYBDENUM Molybdenite or Molybdenum Sulphide. ' "Usually foliated, massive, or in scales; also fine granular. H. 1 1.5, being easily impressed by the nail. G. 4.4 4.8. Luster metallic. Color pure lead-gray. Streak similar to color, slightly inclined to green. Opaque. Laminae very flexible, but not elastic. Sectile, and almost malleable. Fine gray mark on paper. Composition: molybdenum 59, sul- phur 41%. Eesembles graphite, but is decomposed b;* nitric acid. 228 PROSPECTING AND VALUING MINES. URANIUM Uraninite, Oxide of Uranium, Pitch- blende. Usually massive and botryoidal; also in grains. H. 5.5. G. 6.4 8. Luster submetallic to greasy or pitchlike, and dull. Color grayish, green- ish, brownish, velvet-black. Streak brownish black, grayish, olive green, a little shining. Opaque. Frac- ture conchoidal, uneven. Autunite, Uranium Phosphate. H. 2.0 2.5. G. 3.0 3.2. Luster pearly to subadamantine. Color citron -yellow to sulphur-yellow. Streak yellowish. Translucent. Torbernite, Uranium Phosphate, Copper Uraninite H. 2.0 2.5. G. 3.5. Luster pearly to subadaman- tine. Color emerald and grass-green, and sometimes leek, apple and siskin-green. Streak somewhat paler than the color. Translucent. Sectile. (The above are usually associated with silver ores.) VANADIUM Vanadinite or Vanadate of Lead. Usu- ally in implanted globules or incrustations. H. 2.753.0. G. 6.67.2. Luster of surfaces of frac- ture resinouSo Color light brownish yellow, straw- yellow, reddish brown. Streak white or yellowish. Subtranslucent to opaque. Fracture uneven Brittle, CHAPTER XIV. USEFUL EARTHY MINERALS, ETC. I. INSOLUBLE. THE value of the deposits of the various minerals grouped under this heading depends on the purity of the article, the quantities in which it is found, the cost of labor and the facilities of transportation, de- fective conditions on any one of these points taking the deposit out of the list of commercially available propositions, as the market value per pound of most of them is exceedingly low, and the number of locali- ties in which they are found proportionally great; while for some of them there is only a limited demand. ASBESTOS is one of the few well-known minerals, its white or greenish white or bluish fibrous appear- ance being so characteristic as to be familiar to all prospectors. In silkiness it may range from long flexible fibers like flax to brittle earthy masses. It is a widely diseminated mineral associated with rocks which contain large quantities of hornblende or augite, it being one of the products of the metamor- phism or decomposition of these rocks, and is conse- quently common among the hornblende-schists and serpentines, which also produce chrome iron and soap- stone, all three minerals usually occurring in the same locality. The great difficulty connected with the mining of this substance is the large quantity of material which 230 PROSPECTING AND VALUING MINES. must be handled to secure any quantity of asbestos, as it usually occurs in small threads, stringers, seams or pockets, irregularly scattered through the contain- ing rock, so that it must be worked in open quarries, and the asbestos sorted by hand from the rock. It varies greatly in character, from short earthy fibers which are brittle and separate with difficulty, the structure running across the seam and not parallel to it, up to long fine silky threads of a pearly white color very much resembling flax. The term "amianthus" is applied to this last variety. The longer and more flexible the fiber, the more valuable the mineral. Asbestos is infusible, but the common notion that articles made of it can be thrown into the fire and thus cleansed of accumulated dirt, is erroneous, as at a red heat the fibers lose their flexibility and become brittle. It is used in the making of fireproof paints, roofing, piston packing, valve packing, covering steam pipes and boilers, fireproof cement, sheet and rolled mill- board, flooring felt, textile fabrics, etc., being often used in combination with hair felts and other sub- stances. It derives its value for these purposes from its indestructibilitj 7 in ordinary fires, and the resist- ance it offers to the radiation of heat, a property which it possesses in common with wool, cotton, feathers and other substances which cannot be safely used in the presence of high temperatures. For fireproof paints the length of the fiber is not essential, but is a desirable quality for packings and the covering of steam pipes and boilers, while it is essential in all textile fabrics. Asbestos being associated with well-marked belts of rock the prospector should familiarize himself with the character and appearance of these rocks at any locality where he may find asbestos, and having done so, trace this belt along the mountain range, as it will be comparatively useless to spend time on the rock strata which lie either above or below it, excepting so USEFUL EARTHY MINERALS. 231 far as they may help him to locate the position of the asbestos belt, where it is covered up by earth or debris^ or not otherwise traceable. ASPHALTUM. Amorphous or without crystalline structure. G. 1 1.8, sometimes higher from im- purities. Luster like that of black pitch. Color brownish black and black. Odor bituminous. Melts usually at about 194 to 212, and burns with a bright flame. The more solid kinds graduate into mineral tar, and through this there is a gradation to petroleum. Asphaltum appears to be a residual deposit, derived from the evaporation of petroleum products. In the United States fche production is confined to the West- ern States, the deposits (which are always found on the surface or near it) occurring in California, Utah and Colorado, being either fairly pure or mixed with earthy matter. The principal source of foreign supply is the island of Trinidad in the West Indies, where, at a place called La Brea, there occurs an asphalt lake of about 100 acres in extent, the product of which is shipped to Europe and the Atlantic seaboard of the United States. In Europe a limestone, naturally and evenly impregnated with bitumen (or asphalt), is largely used with good results, It is used for many purposes where a surface imper- meable to water is required, combined with toughness. Natural asphalt rock, and asphaltum in combination with other materials, are used in the surfacing of streets and sidewalks, and the finishing of roofs. Asphaltum makes a durable coating for water-pipes. BARYTES. This mineral, also called "heavy spar," because of its great weight, is a sulphate of barium. Its specific gravity is about 4.5, while that of lime- stone is only 2.5. It is an earthy mineral resembling limestone, ranging in color from white through shades of yellow, gray, red and brown to dark brown, accord- ing to the amount of impurities present, but when crystallized has a vitreous or glassy luster and a white 232 PROSPECTING AND VALUING MINES. streak when scratched. Some samples when rubbed give off a fetid odor. It is not affected by acids, and may thus be readily distinguished from the limestones with which it may be associated, as well as by its weight, which is much greater than any of the similar minerals, such as gypsum and carbonate of magnesia. It occurs in veins and beds associated with lime- stones, sandstones and trap rocks, and not infrequently forms the gangue, wholly or in part, of metallic veins, especially those of lead. The mineral is widely dis- tributed, occurring in beds in sandstones in Connecti- cut, and at Isle Royal, Lake Superior; in beds in lime- stone in Iowa and New York; and in limestone and associated with lead ores in Missouri, North Carolina, Tennessee and Virginia. On the northern shores of Lake Superior veins occur in trap rocks. Barytes is used very extensively in the arts, but almost altogether for purposes of adulteration, for which its leading use (about 90%) is in replacing to a greater or less extent white lead in paint. The claim is made that a mixture of one-third white lead, one- third oxide of zinc and one-third ' 'floated " barytes makes a better paint than pure white lead. It is also employed as a "filling" for general purposes, in pulps and in making putty and pottery. The value of ground barytes being not much over one cent per pound it is evident that only the purer deposits and those best located for dressing and transportation can be made available. It must be free from grains of quartz, iron rust and other impurities, and of a good white color. BAUXITE. G. 2.5. Color whitish, grayish to yel- low ocher, brown and red. Occurs in round concre- tionary disseminated grains; also massive oolitic; and earthy, clay-like. Bauxite occurs in the United States in the Coosa Valley, Georgia and Alabama, in clay beds along the line of an extensive fault in lime- stone rocks, the beds having apparently accumulated USEFUL EARTH T MINERALS. 233 in depressions eroded along this fault, no eruptive rocks being present; also in Arkansas, in regularly stratified beds near the contact with eruptive rocks, and in France as a residual deposit from the decay of basaltic rocks. In Styria, a deposit 12 ft. thick occurs at the junction of theTriassic and Jurassic formations. The favorite associations appear to be limestone and eruptive rocks. From the large amount of alumina present in bauxite it forms a valuable source of aluminum, and the purer varieties are largely used in the production of that metal, being known as "aluminum ore. " On the Con- tinent of Europe the product of the quarries at Baux in France, from which the mineral takes its name, is also used as a flux in iron smelting. It is difficult to give a concise description of this valuable ore, but the following extracts from "Mineral Industry," Vcjl. II., will probably be sufficient to call attention to its chief peculiarities, and to suggest the desirability of submitting suspected samples to analysis: "Bauxite has few specially distinctive char- acters except its usual pisolitic (pea-like) or concre- tionary character, which perhaps accounts for its hav- ing been so long overlooked, and for the comparatively few localities where it is known to occur. The red variety of bauxite was thought to be pisolitic iron ore until its true character was shown by analysis. "Bauxite is usually a concretionary or pisolitic min- eral, though sometimes it is a hard, compact, homo- geneous, fine-grained rock, commonly oolitic (made up of round egg-like fragments), and sometimes an earthy, clay-like material. It may therefore be hard, or soft and friable, compact or porous, but the best grades are hard and have a metallic ring. The con- cretions vary in size from small peas to large bowlders, which are cemented together by fine-grained hard bauxite, bauxite clay or silicious material. In nearly every case, however, the concretions or nodules are 234 PROSPECTING AND VALUING MINES. better mineral than the cementing material. The con- cretions, also, are usually harder than the cementing material, especially in the surface ores. "On the surface, bauxite beds are generally marked by hard, rough bowlders or loose nodules and pebbles in the top soil. Below the surface, however, the nod- ular and pebbly ores are often comparatively soft and crumbly, and the compact oolitic and line-grained ores -are sometimes a soft powder. "Bauxite varies in color from almost pure white to a deep red or black. It is also of cream and pearl- white color, grayish, yellowish, amber, pinkish, and speckled or mottled. . . . These colors often shade into one another, sometimes suddenly and some- times gradually, and it is seldom, if ever, that a bank or deposit is wholly or uniform!}" of one color." CLAYS are essentially silicates of alumina with combined water (hydrated aluminum silicates), but vary immensely in composition, not only from differ- ences in the amount of silica and alumina present, but also from the presence of impurities such as lime, soda, potash, sand, magnesia and iron oxides which affect the fusibility of the mass. It is these differences which render "them suitable for different purposes, For commercial use they may be classed as fire clays, pottery and kaolin clays and brick clays. Fire Clay. The presence of alkaline matter andiron oxides tend to promote vitrification, and an excess of alumina causes shrinkage in burning, so that a good fire clay should consist practically of silica and alumina, with the smallest amount possible of iron and alkali, it being possible to counteract the contractibility or shrinkage by the addition of quartz sand. The pres- ence of an excess of alumina, however, renders the clay more tenacious and plastic, but this is not essential in a firebrick, though desirable in pottery clays. The following table shows the relative composition of five English fire clays and 14 American samples: USEFUL EARTHY MINERALS. ANALYSES OF FIRE CLAYS. 235 a | jj '55 | sandstone or quartzite. 246 PROSPECTING AND VALUING MINES. Beds of sand and sandstone are common everywhere, but they are not all available for the same class of work on account of the associated impurities, and their value for any particular purpose can only be thoroughly ascertained by working tests. The finest kinds of transparent quartz, known as " rock-crystal," are or rather were extensively used in the manufacture of spectacle glasses, but the improve- ments in glass making have diminished this applica- tion. Similar quartz is used extensively in glass and pottery making, and as a grinding and polishing powder. Ground quartz is also used in the manufac- ture of sandpaper. In addition to these a peculiar variety of sandstone called "ganister" is largely used in the lining of vessels used in the manufacture of steel on account of its excessively refractory character. In England the ganister preferred for lining is a peculiar silicious deposit found under a thin coal seam near Sheffield, of almost conchoidal fracture, thereby differing from ordinary sandstone, and containing a few tenths per cent., or sometimes a little more, of lime, and the same amount of alumina, with small quantities of iron oxide and alkalies, the rest being silica; analagous substances are found, however, in other localities in the northern coal tields. Beds of such quartz in the vicinity of steel works are valuable. For mortar making, river sand is preferable, as salt from sea sands will certainly make its appearance on brickwork where it is used, spoiling the looks of the building as well as being objectionable on account of absorbing moisture; it is also sharper, with less rounded angles, as in rapid streams much of it is car- ried down suspended in the water and the angles scarcely suffer any abrasion. STRONTIA, STRONTIANITE, ETC. The metal strontium occurs as a carbonate, under the name of strontia- nite, and as a sulphate, under the name celestite. When crystallized strontianite has a hardness of 3.5 4, and USEFUL EARTHY MINERALS. 347 a specific gravity of 3.65, with a vitreous or resinous luster, and white streak. In color it is pale asparagus- green or apple-green ; white, gray, yellow and yellow- ish brown. Transparent to translucent. (Dana.) It occurs in the United States in granular and columnar masses in hydraulic limestones at Schoharie, N. Y. ; and at Muscalonge Lake in the same State, a massive and fibrous variety of a white or greenish white color is found associated with fluorspar. In Scotland it occurs in veins traversing gneiss, along with galena and bante (barytes). (Dana.) Celestite has a hardness of 3 3.5 and sp. gr. of 3.95, being somewhat softer and heavier than stron- tianite. The luster is vitreous inclining to pearly when crystallized, and the streak white. The color white, often bluish (from which it takes its name) and sometimes reddish. More or less transparent. (Dana.) Celestite is usually associated with limestone or sand- stone, and occurs also in beds of gypsum, rock salt and clay. (Dana.) In the United States it is reported from the limestones about Lake Huron ; from New York and Pennsylvania, and also from Green orStron- tian Island, Lake Erie. Nitrate of strontia is used to a considerable extent by the makers of fireworks for the production of red fire. The use of strontia has also been proposed in the treat- ment of beet sugar, and in the manufacture of tuyeres for blast furnaces. Sicily furnishes the bulk of the mineral at the present time, but little search for it having been made in the United States on account of the small demand. SULPHUR cannot be mistaken for any other mineral, its brilliant yellow color, and characteristic odor on burning, separating it instantly from all others- "Wherever found it appears to be associated with vol- canic action and hot springs, having been deposited by such agencies in vast beds both in Europe and America. In boring for petroleum near Lake Charles, 248 PROSPECTING AND VALUING MINES. Calcasieu Parish, Louisiana, "at a depth of 423 ft. the drill passed through 100 ft. of pure sulphur and 148 ft. of gypsum mixed with sulphur, the former mineral being a common associate of sulphur deposits, by the conversion of ordinarj 7 limestone into the sulphate through the action of sulphuric acid. In Nevada, the beds near Silver Peak are traversed by seams of alum, formed in a similar way by the decomposition of aluminous or clay-forming rocks. In California, at the Sulphur Banks in Lake County, the deposits are associated with cinnabar or mercury and borax. In Southern Utah the occurrence is evidently in what was formerly a crater of a volcano, about three miles from Fort Cove Creek. The crater forms a small basin sur- rounded by low hills with a narrow ravine opening into the plain probably a breach in the old crater wails which consist mainly of andesite with some pale whitish trachyte (both porphyries) with obsidian splinters scattered over the surface. As far as explored the sulphur beds extend over an area of at least 1,800 by 1,000 ft. across. The sulphur shows upon the sur- face over part of the basin, but is mostly covered with sand, or rather the disintegrated andesite of the sur- rounding hills. A curved cut through the western end of the deposit exposes a vertical wall of rich yellow sulphur 34 ft. high, from which in many places, as well as in other prospect-holes, gases escape, together with water holding various salts in solution." "At the Mammoth claim in the same neighborhood, the slates and limestones are impregnated with sulphur, gypsum being also found as a product of altered limestones; while at the Sulphur King claim the andesifes are similarly saturated." The depositio'n of sulphur is constantly going on at volcanic vents and many hot springs. "Mount Purace, in Colombia, wears a cap of sulphur (derived from its own crater) which accumulates at the rate of 2 ft. per annum its superficial area amounting to 1,435 sq, USEFUL EARTHY MINERALS. 249 yards;" and the sulphur forming in the crater of Popo- catapetl, in Mexico, is regularly worked by the Indians. The salfatara of Bahara Saphinque on the Red Sea is said to yield 600 tons of sulphur annually. American sulphur comes into sharp competition with that pro- duced by the Sicilian deposits (which have been worked to a depth of over 300 ft. and turn out annually 400,000 tons of clean sulphur), and can consequently only be profitably exploited under the most favorable conditions of labor and transportation aided by local demand, which it fostered by the high rates of freight on sulphuric acid on account of its dangerous char- acter. Native sulphur is also met in the market by acid produced from iron and copper pyrites, which are now mined in enormous quantities for that purpose, as the contained metals furnish a valuable by-product. The larger portion of the entire product of sulphur is used in the manufacture of sulphuric acid, the consumption of which in manufactures is extend- ing daily. Outside of this it is employed in the pro- duction of vulcanized rubber goods; in the manufac- ture of "bluestone, " or sulphate of copper, which is largely used in metallurgical operations; as a preven- tative of and cure for mildew on plants by horticul- turists, and many minor uses. TALC AND SOAPSTONE. H. 1 1.5. G. 2.65. Luster pearly. Color apple-green to white, or silvery white; also greenish gray and dark green; brownish to blackish green and reddish when impure. Streak usually white; of dark-colored varieties, lighter than the color. Easily cut with a knife. Thin sheets flexible, but not elastic. Feels greasy. (Dana.) The foregoing description is of the purer and softer varieties, from which the harder kinds are separated as "soapstone, " to the best kinds of which the term "French chalk" is applied. The mineral is soft enough to leave a whitish mark on cloth, and is used by tailors in drawing their patterns. The various forms of talc are 250 PROSPECTING AND VALUING MINES. of very common occurrence; and steatite or soapstone forms extensive beds in some regions, being often associated with serpentines, chloritic or talcose schists, in which latter rock thin flakes of talc take the place of mica, and impart to it a certain greasy feel, which is characteristic of the entire series of minerals asso- ciated under the name, which is often applied by miners and prospectors to any soft white earthy substance in the gouge of veins, whether greasy or not. Talc is used extensively in soap making, and in dressing fine sheep-skins, leather, gloves, etc. The finer, soft, foli- ated variety is used in the manufacture of paper, and small quantities enter into the composition of some lubricating compounds. "Soapstone," OD account of its refractory nature in the presence of intense heat, and the facility with which it can be sawn into bricks, slabs or any desirable shape, is extensively used as a lining for stoves, furnaces, etc. It can be easily turned in a lathe, and the writer has seen on the Mexican border a very ancient tuyere for a black- smith's forge made out of such material. It was found in grading for a ditch, and from the size of the trees growing over the spot must have been buried for at least 100 years, and may possibly be a relic of the early missionary days of California. II. SOLUBLE MINERALS. With the exception of common salt, which is of gen- eral distribution, and Stassfnrt salt and its associ- ates, the balance of the useful minerals of t'his group all occur in arid regions, where the climatic con- ditions favor the evaporation of the water which dis- solves the various salts and holds them in suspension. Many of them are found in foreign countries where the price of labor is extraordinarily low, and from which ocean carriage is remarkably cheap, so that the products of the United States being found far inland, in thinly populated regions and often in consequence USEFUL EARTHY MINERALS. 251 far from convenient lines of transportation, can with difficulty compete with the imported articles. The efflorescences or crusts of borate of soda, carbonate of soda and salt greatly resemble each other, but can be separated by the tests given in the description of these minerals, the presence of carbonate of soda being indi- cated by effervescence if citric acid be added to a solu- tion of the incrustation,, The compact massive deposits found underlying these incrustations may also be tested in the same manner, and while under existing conditions of trade and transportation they may not be available for other than local consumption, they may possibly supply a mineral which will render others available, just as cheap soda is necessary to make quartz sand valuable for the production of glass. BORAX. H. 2 2.5. G. 1.7. Luster vitreous to resinous, sometimes earthy. Color white, sometimes grayish, bluish or greenish. Streak white. Trans- lucent to opaque. Bather brittle. Taste sweetish- alkaline. Imparts a clear green color to the flame. Boiling water dissolves double its weight of borax. (Dana.) Borate of Lime, Ulexite or Hayesine. H. 1.0. G. 1.65. Color white. Tasteless. Loose in texture, fibrous and silky, usually in rounded masses. Crystallized borax (or borate of soda) is found in the mud of certain lakes both in California and Asia, but the great bulk is produced from the borate marshes of Nevada and California, of which the general character is well described in the Geological Survey reports of 1883. "The borate fields are situ- ated in the extensive salines known as Teel's marsh, Bhodes's marsh, the Columbus marsh and Fish Lake Valley, all in the southeasterly part of Esmeralda County. These salines consist of oval-shaped alkali flats occupying the centers of immense basins, and cover from 10,000 to 20,000 acres each. These basins are surrounded for the most part by a broad margin 262 PROSPECTING AND VALUING MINES, of sage plains which rise gradually to the base of the hills and mountains which inclose them on every hand. They have no outlets, and, receiving the drainage of the country around, retain everything brought into them, including the borates and salts of various kinds. From midsummer till late in the spring, when the snow commences to melt on the mountains, these saliniferous lands are, as a general thing, apt to be dry, only shallow lakes occupying sometimes their points of greatest depression. At other seasons of the year portions of them are covered with water to the depth of a foot or two. Heavy rains, though these seldom occur in these regions, con- vert these alkali flats into beds of tenacious mud, even a slight shower rendering their passage by teams dif- ficult for the time being. Water can be obtained on these salines almost anywhere by digging from 2 or 3 to 10 or 15 ft. below the surface. It is general!}' brackish, however, often so much so as to be scarcel^ fit for drinking. By digging to much greater depths good water is obtained a short distance back from the edge of the marsh. Over large sections of these flats exist deposits of common salt, carbonate of soda, and borax. This latter mineral does not, however, occur here, as at Clear Lake in California, in the shape of compact, semiopaque crystals imbedded in mud, but generally in the form of borate of lime or soda. The former is found at many spots imbedded in these marshes from 1 to 4 ft. below the surface.* It crystal- lizes in long silky fibers which gather into balls from an eighth of an inch to 2 or 3 in. in diameter. These globular masses have the luster of white satin, and when dug up readily separate from the inclosing earth. The borate of soda mixed with sand and other impurities accumulates on the surface in the shape of a dark-colored incrustation an inch or two thick. This crust when dry, being hard and brittle, can be easily detached from the moister ground beneath and broken into fragments/' USEFUL EARTHY MINERALS. 253 While Nevada and California are the only produc- ing States in North America, there are extensive deposits in Europe, India, Peru and Asiatic Turkey, and competition has reduced the price from the old standard of 25 or 30 c. per Ib. to a very low figure, the reduction having, however, opened up new avenues of use. The leading uses of borax are in welding (for which the greater part is consumed in iron and steel manu- facture); in refining metals as a crucible flux; in enamelling; by packers, in preserving meat; and as a detergent for household purposes. CARBONATE OF SODA OR TRONA. H. 2.5 3.0, G. 2.10. Luster vitreous, glistening. Color gray or yellowish white. Translucent. Taste alkaline. Not altered by exposure to a dry atmosphere. (Dana.) Soluble in water and effervesces with acids. Trona is another of the minerals occurring as the result of the evaporation of water in dry inland basins without drainage outlets. The following description of one such deposit will convey a good idea of them all : "This mineral abounds throughout most parts of the Great Basin, the extensive alkali flats which form a feature of that region constituting the principal sites of these deposits, which occur usually in the form of an efflorescence an inch or two thick on the surface, but sometimes in strata a foot or more thick imbedded in the earth, and separated from each other by thin seams of clay. When found in the form of a thin incrustation on the surface it is never pure, being always admixed with salt, borax, lime, magnesia and other minerals. The heavier deposits are compara- tively free from foreign matter, carrying generally about 90% carbonate of soda. One of the most re- markable repositories of this mineral known consists of a circular basin, the bed of a former lake, situated on the southerly margin of the Forty-mile desert, Churchill County, Nev. This basin, which covers 254 PROSPECTING AND VALUING MINES. an area of 10 or 12 acres, is depressed 60 ft. below the common level of the country adjacent. Its bottom, usually dry, though in wet seasons oovered with a few inches of water, is composed of a compact mass of the carbonate of soda so hard that it ,has to be broken out with crowbars, and so pure that it can for many pur- poses be used to advantage in its natural state. This substance occurs here in layers about 1 foot thick, separated from each other by thin seams of clay. Large quantities of the crude material are extracted every year. " This deposit has been worked over an area of several acres to a depth of 10 or 12 ft. without showing any signs of exhaustion. A portion of the product from the above locality is used in the working of the neighboring silver ores, but the greater portion is refined and sold for other purposes, soda being very extensively employed both in the arts and manufac- tures. NITRATE OF POTASH, NITER OR SALTPETER. H. 2,0. G, .1.9. Luster vitreous. Streak and color white. Subtransparent. Brittle. Taste saline and cooling. Deflagrates vividly on burning coals, and detonates when mixed with combustible substances. (Dana.) Dissolves easily in water and is not altered by expo- sure. Colors the flame violet when burned. It occurs as an efflorescence on the surface or in the surface stratum of the soil in many parts of the world, but especially to a great extent in the valley of the Ganges and other parts of India, as well as in Spain, Egypt and Persia. It is also obtained in a semi-artificial manner in nitaries or saltpeter plantations. These consist of heaps of decomposing animal matter, mixed with lime, ashes, road scrapings and other rubbish, covered over from rain, and from time to time damped with the runnings from stables and other urine. Such heaps develop within them small proportions of the salt, and other nitrates, and are in effect artificial imitations of the saltpeter-bearing soil of India. USEFUL EARTHY MINERALS. 255 Niter requires for its formation dry air and long periods without rain, and is produced most abun- dantly during hot weather succeeding rain. The potash comes mainly from the debris of feldspathic rocks in the soil. (See chapter on rocks for the per- centages of potash in various kinds of rocks.) It also forms abundantly on the walls of caverns and in the loose earth floors of the same, which abound in the limestones of the Mississippi Valley in Kentucky and Tennessee. It is now prepared artificially from Chili- saltpeter and the German chloride of potash, by mutual decomposition, producing chloride of sodium or common salt and nitrate of potash, or saltpeter/and this product has largely supplanted the native article, being a much superior material. India furnishes the bulk of the imported niter. NITRATE OF SODA OR CHILP-SALTPETER. JL 1.5 2.0. G. 2.0 2.3. Luster vitreous. Color white; also reddish brown, gray and lemon-yellow. Trans- parent. Bather sectile instead of brittle. Taste cool- ing. Deflagrates with less violence than niter, and colors the flame yellow ; also absorbs water on ex- posure to moisture and deliquesces. (Dana.) Chili saltpeter occurs on exceedingly dry and arid plains in North and South America chiefly. In South America in the district of Tarapaca, Northern Chili, the dry pampas for 40 leagues, at a height of 8,300 ft. above the sea, is covered with beds of this salt several feet in thickness, along with gypsum, common salt and glauber salt, with remains of recent shells indicating the former presence of the sea. The arid plains of the Great American basin present almost identical condi- tions as regards altitude, climate aud rainfall (on the Nevada deserts only about 4 in. annually), and as might have been expected, this mineral is found on the 40-mile desert near Lovelock's Station, crystallized in the crevices of rocks and imbedded in the earth from 2 to 30 in. below the surface. Its occurrence is 256 PROSPECTING AND VALUING MINES. also reported in a similar country near Calico, San Bernardino County, Cal. ; and in the southern part of New Mexico, near tbe Chihuahua line, the mineral is said to be deposited by springs in considerable quan- tity. Nitrate of soda is used extensiveb r in the pro- duction of nitric acid and saltpeter or nitrate of potash, the latter product entering into the composi- tion of gunpowder. SALT is sufficiently well known to be distinguished from other similar minerals, when in comparatively pure condition, by its taste alone. Rock salt occurs as immense beds formed by the evaporation of sea water, associated with deposits of gypsum and other marine products. Percolating waters dissolve these accumu- lations and supply the brines for the salt wells of Michigan, New York and other Eastern States, which vary in depth from a few up to 1,000 ft., the average depth in Michigan being 882 ft. ; in New York, 322; Ohio, 932; Pennsylvania, 883; and Virginia, 1,042 ft. The shallowest wells are in Utah, Texas and Kansas. Some brines are obtained not from beds of pure rock salt, but from strata of salt-bearing rocks such as sandstone, shale, etc. The brines from these wells are evaporated by artificial heat. In California, solar heat is extensively used in the neighborhood of San Francisco in the evaporation of sea water; while in Nevada salt is abundant in all the interior basins either as beds of rock salt, as incrustations on the sur- face, which are renewed as often as they are removed, and that so rapidly as to afford several crops annually, or as massive deposits, covered with slight deposits of sand or clay. SULPHATE OF SODA. H. 2.03.0. G. 2.6. Luster vitreous. Color white to brown. Translucent. Wholly soluble in water. The occurrence is very similar to that of carbonate of soda just described, the material being found extensively in lakes and beds in USEFUL EARTHY MINERALS. 257 the States of Wyoming and Colorado, and in smaller quantities in New Mexico. Well known localities are the lake near Independence Rock and the lake seven miles from St. Mary's Station, both in the Sweetwater valley; and Burclsall's Lake near Morrison in Colo- rado. While outwardly appearing much the same, analysis develops the occurrence in the deposits of car- bonate of soda, and common salt, in varying propor- tions, as well as various impurities such an silica, lime and magnesia. Available in the manufacture of soda, glass and gunpowder. III. LIQUID. PETROLEUM. Crude petroleum varies considerably in composition and density, the latter varying from 0.60 to 0.80, forming the so-called light and heavy oils. The light oils give proportionately more illumi- nating oil (kerosene); the heavj 7 , more lubricating oil and residue. It is a hydrocarbon, standing inter- mediate in the series ranging between the asphaltum group of minerals at one end to the lightest naphthas at the other. Its exact origin is in dispute, but is probably the decay of animal and vegetable substances under peculiar conditions. It is usually dark green- ish brown in color, and is easily recognizable by its peculiar fetid odor. Its inflammability varies and is not always a reliable test, as some specimens (of the heavy or impure varieties) do not ignite very readily. In the United States the light oils are found mainly in the eastern fields; from Ohio westward the oils are usually of the heavy variety. It occurs in porous sedimentary rocks of all kinds, as in sandstones, shales and some limestones; and in point of geologic age all the way from the Silurian to the most recent. At the surface it appears as springs, pools and as a scum floating upon the water. The surface prospecting consists merely in following streams showing such oil films up to the source of the petroleum spring or oil-bearing rock 258 P INSPECTING AND VALUING MINES. outcrop. Borings for oil in depth are generally di- rected in accordance with the results found in existing wells of the neighborhood ; though sometimes bore holes are put down in localities far from any previously sunk wells, where geologic reasoning shows the proba- bility of the presence underground of oil-bearing strata which have been proved elsewhere. Boring for oil is a special trade, based partly upon theoretical and geological considerations but more especially upon local experience. iv. GASEOUS. NATUKAL GAS also is a hydrocarbon, something like the "marsh gas" which sometimes rises from swamps, and also related to the "fire damp" of coal mines. It is colorless and odorless, and is lighter than ordinary illuminating gas. Its discovery in a new locality usually results from accidental ignition ; in regions where it is already known to exist borings for it are put down in accordance with the indications given by earlier gas wells, or to strike a stratum which has been gas-bearing elsewhere. CHAPTEE XV. COAL, THE literature of coal is so extensive and complete, and coal mining is so essentially a business in itself, that in a work intended chiefly for the use of the pros- pector for ores a long account of coal would be useless and out of place. This chapter will therefore be de- voted to the presentation of only those points which may be serviceable to the prospector who may come across outcrops of coal while searching for other minerals, so that he may be able to estimate their value as aids in the reduction of metallic ores. ORIGIN. The general origin of all coal beds is the same. Masses of vegetation were laid down in water in a horizontal position, or nearly so; and then, ow- ing to geological changes, covered up and buried by the rocks we now find above them, undergoing in process of time, through pressure and heat, certain chemical changes, which, according to the period of time which has elapsed since their formation, have been more or less extensive; so that to-day we recog- nize several varieties, distinguished chiefly by their percentages of carbon and volatile matter, imparting to them different qualities. The character of the rocks on which beds of salt, gypsum, iron ore, etc., are deposited is purely accidental and unimportant, but in the case of coal the wide marshes demanded a reten- 260 PROSPECTING- AND VALUING MINES. tive bottom to prevent drainage, and we consequently usually find a floor of clay, often fire clay, without which we cannot imagine the formation of such enormous accumulations of vegetable matter, which before compression reduced them to their present con- dition must have had a thickness from ten to twenty times that which they now exhibit. The edges of coal deposits are likely to be largely contaminated with sand and clay or other waste matter; and it is easy to see, if the deposit be of small area, how this worthless margin may form a much larger proportion of the whole bed than in those of greater extent, as in the case of coal we must picture to ourselves immense level marshy tracts, covered with a dense, luxuriant vegetation which would certainly intercept any wind- blown debris before it had traveled far from the margins of the swamp, or would entangle in its roots the sediment brought down by streams, the velocity of whose currents would be promptly checked, and con- sequently they would drop their burden. COMPOSITION. As a general proposition the percent- age of carbon is greatest in those coals which are the oldest geologically. Coal contains a certain amount of "fixed" carbon, or that which remains after coking, and also a certain amount of carbon in com- bination with hydrogen, oxygen and nitrogen, forming the volatile portion ; the remainder is earthy matter (forming ash) and moisture. The following table, from Andre's "Practical Treatise on Coal MiniDg" (which may be consulted for all details), is very in- structive, showing that with age, in the sense of geo- logic time, coal loses the gaseous elements, particularly oxygen and nitrogen, consequently containing a larger percentage of carbon, and steadily increasing in specific gravity. An important exception is found in the case of comparatively recent coals which have been heated and altered by the proximity (not actual contact) of igneous dikes or overflows, producing the COAL. 261 same effect as age. Colorado and are examples. The percentages spective of ash and moisture. are other anthracites calculated irre- COMPARISON OF CARBONACEOUS SUBSTANCES. Substance. Specific Gravity. Carbon. Hydro- gen. Oxygen and Nitrogen. Wood mean of 12 kinds Per. Cent 0.91 0.99 1.25 1.27 1.30 1.37 1.50 Per Cent. 49.00 59.30 72.37 80.07 86.17 91.00 92.50 Per Cen 6.25 6.52 5.18 5.53 5.21 4.75 3.75 Per Cent. 44.75 34.18 23.45 13.50 8.62 5.25 3.75 Peat mean of 12 samples Lignite mean of 12 samples .... Cannel coal Bituminous coal mean of 3 divi- sions Semi-bituminous coal mean Anthracite coal mean CLASSIFICATION. 'The classification and names of coal are based on the foregoing percentages. A portion of the gases are combined to form water, while the re- mainder of the gases are combined with a portion of the carbon in the form of volatile matter, leaving a balance of carbon, which is known as the " fixed" car- bon, and is that portion which is left as coke when the volatile matter has been extracted by distillation. The varying proportions of these materials render the different kinds of coal suitable for different purposes. Water in all cases is a detriment to the coal, as it must be driven off in th form of steam at the expense of a portion of the carbon, which is thus lost for heating purposes. The following classification of coals is taken from Andre, and is based on the amount of coke produced by distillation. The "coke" in this case does not mean commercial coke, but the residue left in labora- tory tests. Neither anthracite at one extreme nor lignite at the other make true coke. PROSPECTING AND VALUING MINES. CLASSIFICATION OF COALS. Name of Coal. Coke, Per Cent. Volatile Matter, Per Cent. Character of Coke. 93-88 8-12 Brittle and powdery. Semi-bituminous 88-82 12-18 Brittle and powdery Bituminous 1 Clear-burning 82-74 18 26 Good. 74-68 26-32 Good. 3 Smoky or fuliginous ... 68-60 32-40 Porous, friable. 60-50 40-50 Soft, powdery. Lignite or brown coal 50 50 DISTINGUISHING CHARACTERS OF COALS. Anthracite Its structure is perfectly homogeneous, its density greater than that of other kinds of coal, and it has a more completely mineralized appearance. Its color is a jet black, with a somewhat vitreous luster, often ex- hibiting a powerful play of colors. It does not (easily) soil the fingers when handled, being very hard and firm. In the harder examples, the fracture is distinctly conchoidal, but when of a more tender character it frequently breaks into small cubical lumps. Anthracite burns with a feeble flame, blue when the supply of oxygen is insufficient, and often decrepitates much in burning. It ignites with diffi- culty, and is slowly consumed, but when in a state of perfect combustion it evolves intense heat. The quality of hardness possessed by anthracite enables it to be transported from place to place without injury, while that of evolving great heat without smoke renclers it peculiarly suitable for many purposes, as in the generation of steam, and employment in distil- leries, breweries, or in lime or brick kilns. In America it is largely used for domestic purposes; also for steam-making on naval vessels at times, and in cities where "anti-smoke" ordinances prohibit the use of bituminous. Semi- anthracite is a term sometimes used to indi- cate a grade between strictly anthracite and semi- bituminous, COAL. 263 Semi-bituminous Coal occurs Dext above the anthra- cites in geological order. Occupying a higher posi- tion, it has been less exposed to the action of heat and other metamorphic agencies, and has consequently retained a larger proportion of its volatile matter. Between the anthracitous and the semi-bituminous classes, however, the line of division is purely arbi- trary, since from anthracite to cannel there is every grade of composition. Its color is usually a dull black and its fracture subconchoidal. It frequently exhibits a peculiar fibrous structure, passing into a remarkable toothed arrangement of the particles, called " cone-in-cone" or crystallized coal. It burns with a slightly more abundant flame than coals of the anthracitous class, and evolves more smoke, but not in dense volumes. It possesses the dry character of the latter class, and from its freedom from a liability to cake together, it is sometimes called "free-burn- ing/' and " steam coal." Bituminous Coal (Clear-burning 1). "The varie- ties of the clear-burning division are the poorest in volatile matter. They are similar in texture to those of the preceding class, but generally of a duller luster. They are very tender, and break with an even or an irregular fracture, and in consequence of the very per- fect development of the cleat* have always a tendency to break up into small cubical lumps. These coals kindle with difficulty, and burn away slowly with a short, clear, bluish flame, and very little smoke. When reduced to a powder and heated in a close vessel they fuse and agglomerate into a dense and strongly coherent coke, a property which renders them extremely- valuable for manufacturing purposes. Both in quality and quantity the coke obtained from the clear-burning coals is superior to that obtained from any of the more bituminous varieties." * Cleat s the system of parallel joints at right angles to the bedding of the coal. 264 PROSPECTING AND VALUING MINES. Flaming Coal (Bituminous 2). "The coals of tbis class are richer in volatile matters than the fore- going, a circumstance to which they owe their char- acteristic flaming quality. Their structure is dis- tinctly laminated, and their color black and glossy. When reduced to powder, however, their color is a dark brown. They kindle without difficulty, and burn away somewhat rapidly with a long white flame. Coals of this class become partially fused when strongly heated, and while in a fused state swell into a spongy mass, giving off bubbles of gas, which burns with a bright flame. This property of agglutinating in the fire allows the small coal to be burned which would otherwise be useless, or to be converted into coke, of which it produces an excellent quality. To this property, also, these coals owe the name of 'cak- ing* coal, which has been applied to it in common with some other varieties of the same class/' Fuliginous Coal (Bituminous 3) " contain a very large proportion of volatile matter. Hence they kindle readily, and burn away rapidly with a long yellow smoky flame. They are somewhat hard and strong, and their fracture is rather shaly. Coals of this character fuse in the fire like the flaming varieties but they do not agglomerate or cake into so compact a mass. The gas obtained from them is abundant and of a high illuminating power, but the coke obtained from this division is friable and porous, and unfit for many purposes. " Gas Coal (Bituminous 4). "All of the foregoing coals occur in the so-called Carboniferous period, but some of the present section are found in beds of later geological times. They are distinguished by the very large proportion of volatile matter which they con- tain, and to this circumstance it is due that they do not cake when heated. Experience has shown that coal becomes caking when the proportion of carbon reaches 80%, and that of the hydrogen descends below COAL. 265 on the other hand, when the proportion of hydrogen becomes very small and that of the carbon large, as in the anthracites, the same non-caking qual- ities result. The gaseous coals are of a brownish black color and of a dull luster. When reduced to powder they are quite brown. They are generally hard, compact and strong; their fracture is even to conchoidal. Coals of this class kindle even more readily than the fuliginous varieties, and they burn away rapidly with a long flame. The coke obtained from coals of this class is of a soft and pulverulent or powdery character and useless for commercial pur- poses." Cannel Goal "naturally falls under the head of a gaseous coal, though differing much in appearance. It is a very hard compact coal, of a black or brownish black color, sometimes glossy, but more frequently dull in luster. It does not soil the fingers when handled, and it is capable of taking a high polish. It breaks with a flat conchoidal fracture, and is distin- guished from ordinary coals by the absence of a laminated structure. This is a mark of its highest perfection, for when it comes earthy and impure the laminated structure is developed. It kindles very readily, and burns away in the hand with a very abundant white flame. It is now employed almost exclusively (except for grate fires) for gas making, for which purpose it commands a high price. Seams of caunel occur in certain districts with ordinary coal, and often form the upper portion of a seam of bitumi- nous coal, and occasionally of a bed of black-band ironstone." The splint coal of West Virginia aad other States somewhat resembles can nel in appearance and qualities, but is higher in the scale of fixed carbon. Lignite or Brown Goal "occurs in the more recent geological formations. The processes of mineraliza- tion having been less completely effected than in the older coals, they exhibit their vegetable structure 266 PROSPECTING AND VALUING MINES. more completely, and as an effect of the same cause they retain a much larger proportion of the volatile matters. In color they vary from brown to pitch black. Their luster is generally dull, but sometimes resinous; the fracture is various. They burn readily with a dull flame, emitting much srnoke, and an un- pleasanfc odor. In consequence of the small propor- tion of carbon and the large quantity of water which the3 r contain, the brown coals do not possess great heating power. They are largely developed in the western States of America. On account of the large amount of water they 'slack' into small fragments when exposed to the air and sun, the large blocks soon showing a multitude of cracks/' IMPURITIES IN GOAL. -In all the foregoing remarks the coal is supposed to be free from impurities, but as a matter of fact this is seldom the case. "The impuri- ties may be classed as essential and accidental; the former being those which entered into the composition of the vegetable substances from which the coal was formed, and the latter those which have been inter- mixed with these substances. The essential impurities consist of silica, alumina, lime, magnesia and oxide of iron, to which may be added water. The accidental impurities may consist of any substance other than the elements mentioned. Some of these have been in- troduced by the infiltration of water holding the sub- stances in solution. In general the accidental impuri- ties consist of earthy matters, which were probably deposited from water flowing among the coal vegeta- tion, or blown thither by the winds. The quantity of earthy impurities present in any given sample of coal is estimated by weighing the ash after combustion. When the weight of the ash so left does not exceed 5% of that of the coal, the latter is considered very pure. Above that proportion it begins to lose in quality and becomes hard and shaly in structure. "A common impurity is iron pyrite, or sulphuret of COAL. 267 iron, a substance known to coal miners as 'brasses.' Pyrite occurs sometimes as a deposit filling the cracks and fissures in the coal; sometimes as thin beds. It is not infrequently met with running with a line of part- ing, or it occurs as crystals disseminated throughout the mass; and more often as minute particles imper- ceptible to the naked eye. The presence of iron. pyrite detracts greatly from the value of coal by rendering it unsuitable for many important purposes. Coal con- taining this mineral is totally unfit for [iron and steel] metallurgical purposes [though available for other metallurgical uses, as in roasting and smelting certain metals], and it cannot be burned anywhere in contact with iron without serious injury to the latter. Hence it cannot be employed for the generation of steam, as its corroding action would rapidly destroy the fire- grating and the lower plates of the boiler. Moreover, pyrite is decomposed by moisture and converted into a sulphate, and the expansion which takes place dur- ing the process tends to break the coal into very small lumps and even to powder. This decomposition is often accompanied by great heat, and spontaneous combustion is not infrequently occasioned thereby. Heaps of brassy small coal and rubbish lying as refuse on the pit bank often take fire from this cause in wet weather, and, which is of far more disastrous conse- quence, the exposed coal in the workings will some- times become ignited." While no coal is free from impurities, the variation is great both as to the amount of ash left after burn- ing and of water. From the nature of the origin of coal, as has been already seen, there must be a thin edge to the bed entirely round its circumference, and this will naturally contain a larger percentage of im- purities than the central mass, "where they may be scattered through the entire thickness of the seam or consist of thin alternate layers. Sometimes one or more of these layers will extend over a large area and 268 PROSPECTING AND VALUING MINES. frequently assist materially in mining the coal. In such cases the upper seam may have quite a different character to the lower one and may be mined sepa- rately. TEST FOB COKING QUALITIES. Some coals -which appear to contain the requisite ingredients to make good coke refuse to coke except under particular treatment, and only a series of analyses, followed by working tests, can determine tha ultimate value of a field, or to what purpose the product may be best adapted; but the prospector may readily ascertain for himself by the camp fire, whether his find comes within the coking series by the following means: Take a clay pipe with a moderately long stem ; fill the bowl with clean powdered coal, and then carefully lute, or stop the top with stiff, well-worked clay. It is not advisable to fill the bowl too full, as if the coal should prove to coke, it will swell on heating, and raise the clay cap, admitting air, and the experiment will be a failure, as the coal will take fire. When pre- pared, place the bowl of the pipe in the fire, heating it gently at first to dry the clay without cracking, and then more rapidly to a white heat. Smoke and gas will be given off (through the stem), which will burn freely, being made up of the volatile matter, water and sulphur. When this ceases the operation is com- plete. Take the pipe from the fire, and if the coal will coke, the bowl will be found to contain a solid mass of ccke of a bright dark gray color, hard and compact, if good; but easily crumbling to powder if of poor quality. If the luting or stopper of clay has cracked it may be partially burned up, but a few ex- periments will easily give the requisite skill to make the test. A large portion (practically all) of the ash, of course, goes into the coke. The ash is determined by weighing the earthy matter left after burning a definite weight of dry coal in the open air (by which the carbon as well as the CO A L. 269 volatile matter is consumed), and calculating the per- centage. Analysis alone can determine this accu- rately and furnish tne information whether it is a high or low grade coal, in case it refuses to coke. COMMEECIAL VALUE. The prospector's interest in a coal discovery centers in the question whether it will become a business success on development. This depends on the number, thickness and dip of the workable beds; on an abundant supply of cheap labor, to keep the cost of mining, sorting and washing at a low figure; cheap transportation by land or water; and freedom from competition with coals of its own class, thus filling a vacant place in the market. Many or all of these items may be largely modified if the coal is found in a region otherwise largely devoid of fuel, as many of our interior mining districts, in which the price might be greatly enhanced, and the product yet have a ready sale: but the conditions be- come emphasized, especially as regards coal for domes- tic purposes, in densely wooded districts like western Washington. But with all conditions apparently favorable, the exploration of the field may result in failure, from excessive and unexpected "faulting" of the coal largely increasing the cost of working; by the intrusion of eruptive rocks into the coal seams, destroying the coal ; by a change in the character of the coal ; by the thinning out of the beds; or the opening of other mines better located with regard to some item which gives them an advantage in the market. PROSPECTING. There is not much to be said on this subject. The first discovery is likely to be purely ac- cidental, but when made a few simple rules will assist in tracing the outcrop. The first thing is to get a good knowledge of the rocks between which the coal is found and their relation to other rocks above and below them, keeping a sharp lookout while doing this for any fossils such as shells or plants. After acquiring 270 PROSPECTING AND VALUING MINES. this knowledge, the search must be confined to the region occupied by these floor and roof rocks, and the knowledge gained of the associated rocks will tell the searcher in which direction he must look, if he acci- dentally has wandered beyond the limits of the coal- bearing series, because, from the way in which the beds were formed originally, they are now found more or less parallel to the junction of two different kinds of rock. If the country has been much tilted the outcrop may follow quite a wavy line or even apparently run in a semicircle, but having by the means just stated defined the limits of the area in which coal is likely to be found, the search may be continued by follow- ing up the ravines which cut this formation. In a densely wooded country this kind of exploration is difficult, but as the coal is softer than the rocks in which it is found, tljere is usually a sharp break or drop in the bed of the ravine at the point where the coal crosses, and all such places should be carefully examined. Beyond this the prospector must use his own judgment. As coal suffers from exposure to the elements, it is likely that the outcrop will be inferior to the coal found at a little depth below, but whenever the roof and floor become solid and show no signs of decay, the coal there found may be taken as a general, but very rough, sample of the deposit. Provided all the surroundings appear satisfactory a complete series of borings should be made to prove the condition of the beds as regards "faulting, " but at this point the work of the prospector ends, and that of the engineer begins. CHAPTER XVI. GOLD GRAVEL DEPOSITS. GRAVEL MINING or washing is carried on to obtain placer gold, platinum, tin, diamonds and some other less important substances, which are found during the search for the more valuable ones. When the water used in the process is applied under pressure, the term "hydraulic mining" is applied to the operation. The deposits operated upon may be glacial drift; the beds and hillsides of modern streams, which are generally called "placers," and the operation "placer mining;" or the gravel accumulated in the beds of ancient streams, long since dry, and not infrequently located high on the mountain sides above all the pres- ent rivers, may be attacked by hydraulic methods, when not covered with a lava cap; or "drifted" by means of tunnels, in a manner similar to coal mining, when the cap of the mountain is too hard to be removed economically, or the top gravel too poor to pay for washing, or water too scant in supply or with too small a head or pressure to admit of hydraulicking. The working of ordinary placers by ground sluices or by sluice boxes is so well .mown that it is not neces- sary here to enter into any details. In studying gravel deposits we must remember that the laws governing the operations of nature have been the same for all time; that the forces have been the same, though they may have operated with greater activity ; and that any explanation of the phenomena which is not in strict accordance with these laws must 272 PROSPECTING AND VALUING MINES. inevitably be erroneous and defective. This caution is the more necessary as we have to deal largely in our explorations with things that we cannot see and can only base our surmises as to their condition on the laws which we know to govern the same circumstances in the world which is open to our inspection. Any proposition which is in direct opposition to these laws should be laid aside promptly as worthless. The importance of this is especially apparent in the open- ing of "drift" mines. ORIGIN OF GRAVEL DEPOSITS. All accumulations of gravel and sand have been made by the action of water, either as running streams or sea waves, or by ice as glaciers and icebergs, and result from the wear- ing away of rocks by the action of the air or rain or frost, or all three combined. The nature of their con- tents must therefore depend on the character of the rocks which have been destroyed and the width, depth and velocity of the streams which carried the material to its resting place, or the area over which ice sheets and glaciers or floating ice could carry its burden of soil and rocks before melting and depositing its load. As we have seen in studying the filling of mineral veins, the minerals are disseminated through a variety of rocks, and the presence of veins is not necessary, as is so generally supposed, to "feed" the stream. When a stream ceases to show gold in the bed on following it upward, it does not follow that there must be a rich vein in that vicinity, for which we constantly find the miners searching; it may be simply an intimation that the upper limit of the gold-bearing rocks has been reached. We can indeed have good placer diggings in regions where well-defined veins are scarce. If we once thoroughly realize this general distribution of gold in certain belts of rock, the origin of gravel deposits carrying gold, tin or platinum becomes much more easily intelligible. When the rock is decomposed by the ordinary action GOLD GRA VEL DEPOSITS. 273 of frost or air and rain, the detached particles are con- stantly descending by the steepest line, under the action of gravity or water, and this is usually more or less at right angles to the stream into which they finally find their way. During this descent the par- ticles of gold suffer but little abrasion, as their prog- ress is excessively slow, and they undergo no sorting into sizes, other than what would result from the greater momentum of the larger particles, causing them to travel further on a steep side hill where but little surface water and rivulets acted; but if there were much water coming down the side hills, the reverse might occur, the larger gold particles resisting more than the light flaky ones. On entering the water their fate depends on the depth of water and the velocity of the stream. If the latter is great, the finer flaky par- ticles, which even in still water descend to the bottom very slowly, will be swept away with the sand on their seaward journey, only the heavier pieces reaching the bottom, where they will continue to sink into the river bed by their superior weight as long as the surface is very soft or slightly agitated. The less the velocity, the smaller will be the amount thus swept away. In cases where the gold has not been much subject to the action of water for continuous periods, it may retain its crystallized or angular form, and this is usually an indication of the vicinity of a vein, especially if por- tions of quartz are still attached to the specimens. The smoothing and flattening of nuggets and grains of river gold is probably due to a large extent, if not alto- gether, to the impact of heavy rocks and the polishing action of sand and gravel as they are swept over it in the river bottom, just as such material polishes and wears away the angles of bowlders or solid masses pro- jecting from the bottom of the stream. It does not seem probable that the coarse gold has ever traveled very far from the point where it first found lodgment in the river, but the very finest particles may be trans- 274 PROSPECTING AND VALUING MINES. ported many miles. Gold derived from the decay of either iron or arsenical pyrites rnay be so excessively fine that it will never find a lodgment on the bottom until the sediment with which it is mixed reaches quiescent or perfectly tranquil waters. RIVER DEPOSITS. 'All rivers and streams may be compared to immense sluice boxes in which the heavier particles have been retained, and the lighter ones washed away, while nature has been carving out the river basins with all the forces at her command, pre- senting for our final clean up the contents of an immense mass of material so inexpressibly poor in gold, platinum, tin, etc., that human efforts could not have undertaken the task. Some idea of the extent of this concentration may be obtained when we remem- ber that we have absolute evidence that some of the river channels in California have been cut down fully 2,000ft. below the surface as it exists to-day. In such a valley with a width of 6,000 ft. from rim to rim, 6,000,000 cu. ft. of rock have bean removed (6,GOOX 2,000-=-2) to carve out one running foot of its length, and all that remains may be a deposit 400 ft. wide by an average depth of 20 ft., or 8,000 cu. ft. to the running foot of the ralley, or in other words 222,222 cu. yds. have been concentrated down to about 300 in round numbers (say 740:1). If the value of this be $1 per yd. the original material would only have contained about one and a third mills in the same quantity ($0.00135). During this process a portion of the finer gold has been carried down the stream to flatter regions by the strength of the current, but the coarser has been retained, probably not far from its source, the extent of the deposit varying considerably with the character of the bottom of the channel, the bowlders in which act the part of riffles or lining in the artificial sluice box. Modern Streams.^ In the case of the modern moun* GOLD GRAVEL DEPOSITS. 275 tain streams, the velocity arid quantity of water have been so adjusted to the amount of material brought down, that the bulk of the finer debris or waste has been carried down to the valleys below, leaving only the coarser gravel and bowlders in the beds of the ravines filled in with a certain percentage of fine ma- terial in the interspaces, making the deposits compar- atively shallow and rich, and there does not appear to have been much change from time to time in the con- ditions under which they were made. Ancient Ewers. When we come to study the ancient or buried streams, as they existed prior to the last great outbreak of lavas, in which the deposits are sometimes 400 ft. thick or over, we shall find evi- dences of great alterations in the flow of water from time to time, and the character and quantity of the material carried by it in suspension. If we trace the history of one of these old river channels, as read by the records it contains within itself, construed by the laws of nature in operation to-day, as in the past, we shall get a clearer idea of their structure than in any other way and be better prepared to open them for success- ful mining. Bedrock; Eim; Grade. The rock on which the gravel deposits lie is called the "bedrock " (see pi. 10, figs. 1 to 6), and the point where the bedrock and gravel or lava are seen in contact on the surface the "rim," as in pi. 10, fig. 4, a,g; fig. 5, a. The inclination of the bottom of the stream in the direction of its flow is known as the "grade" of the channel. By com- parison with known mountain ranges, it will be seen that all streams have steep grades near their sources, becoming flatter and flatter as they approach the low- land valleys. Bottom Gravels. The first stage was similar to the conditions surrounding our modern streams. The wearing away of the hills was carried on comparatively slowly, the streams were of moderate velocity, carry- 2?6 PROSPECTING AND VALUING MINES. ing off the waste and leaving the coarse gravel and gold in the river beds. Large quantities of material brought down in flood time were gradually panned out during the drier seasons, as we know by the thin layers of iron sand, such as we see cleaned up by the lap of the stream on our present river banks and sea beaches, leaving the contained gold to enrich the bot- tom deposits. In this way the so-called " bottom" gravels, which are the exact counterpart of the modern placers, were formed, by the alternate flood deposits and slackwater panning. These bottom gravels are usually the only ones which will pay for the slow process of drifting; and sometimes, when too poor for this method of working, the entire "top dirt" has to be removed, even if it barely cover expenses. The Deep Beds. Then commenced a change in the surroundings. The quantity of sediment sent down had been so great that the streams at the mouths of the mountain valleys became filled up and the sedi- ments began to accumulate in the valleys themselves, and from that time the material deposited assumed a flat grade, and the filling up of the bed of the stream proceeded at a rapid rate, creeping upward as the lower portions became more and more choked, until in some cases we find the thickness of these beds run- ning up into the hundreds of feet. The gold in such material is naturally fine, and not having undergone the process of concentration to such an extent as the bottom gravel is much less in quantity for equal bulk of material; but there is no sharply defined line be- tween the two, although the depreciation takes place rapidly until the general average value of the upper fine beds is reached. This results from the fact that there is to some extent a combination of both condi- tions at or near the point where the flat grade of the valley met the steeper slope of the mountain stream. As the valley filled up the river channel naturally be- came wider, the sheet of water thinner and in conse- GOLD GRA VEL DEPOSITS. 277 quence less and less able to carry any burden in sus- pension, and it is easy to picture a wide sandy bottom with changing channels, bars and stagnant pools ob- structed by snags and log jams. All the conditions are beautifully shown in the deep gravel workings at Sailor Flat in Nevada County, Cal. PI. 12, fig. 7, shows a portion of the gravel bank at this place, and the constant changes of the channels can be read in the various deposits of sand and gravel lying uncon- formably on each other. The black marks in this figure show the position of pieces of petrified wood, which is found in enormous quantities in every con- ceivable form of petrifaction. Sometimes the trees are imbedded singly; at other points they have ac- cumulated on bars aud are massed together as we see them in modern streams after floods. In the shallow pools, the falling leaves have accumulated in the fine silt or mud, which now splits in very thin layers, and reveals a wonderful variety of leaves, the imprints of which are in an excellent state of preservation. That there were occasional periods of drought when the water was comparatively free of sediment, yet with a velocity sufficient to pick up and remove the finer sand to a certain extent, is shown by the thin beds of fine gravel which can be seen on the face of the bank, and which by their superior richness indicate a certain amount of concentration, as in the bottom gravels. In a few cases these beds have become sufficiently thick and enriched to pay for drifting, as in the case of tbe Breece & Wheeler mine in California, of which a gen- eralized cross section is shown in pi. 11, fig. 2. The upper tunnel was run on such a deposit, so cemented together by the iron which remained among the gravel, as a part of the concentrates, that it had to be crushed in a mill to save the gold. On pi. 10. fi^s. 1, 2 and 3, the so-called top dirt is shown by c, the bot- tom dirt being indicated by the solid black at g. The modern placer deposits are shown at e t e,e. 278 PROSPECTING AND VALUING MINES. Pipeclay. The beginning of the third stage com- mences with the renewed volcanic activity. The de- position of sand and gravel ceased and immense beds of clay, called by the miners " pipeclay," sometimes reaching a thickess of 200 ft, as at Cherokee Flat in Butte County, were laid down. Afc other points we have deposits of rounded bowlders like cobblestones, and it is not unlikely that these deposits were derived from the earlier outbreaks of the volcanoes, accom- panied by excessive rainfall, which washed the ejected matter into the ravines, the finer material, as in all other cases, being carried furthest from its source. Most of the bowlders in ordinary placer ground are merely waterworn fragments of local rocks; the large proportion of quartz bowlders being due to their hard- ness. It is certain, however, that immediately succeed- ing these bowlders and clay, immense outbursts of lava poured into the river bottoms and filled them from bank to bank. A case where a bed of sinter (volcanic ash) separates unconformable gravel beds is shown in pi. 12, fig. 6, where the sinter bed appears to have been tilted after deposition. Lava Cap. Some of the lava beds are over 100 ft. in thickness and form to-day conspicuous objects in the landscapes of the gold regions of California, where they cap hills called "table mountains," from their nearly level summits as seen against the sky, and their precipitous sides. In pi. 10, figs. 1, 2 and 3, the pipe- clay is shown by b and the lava cap by a. With the formation of the lava cap the process of filling was completed. PI. 10, fig. 1, shows the order of succes- sion -bottom gravel, g; fine gravel and sand, c; pipe- clay, b; lava, a. The dark shaded portion shows a cross section of a mountain with its ravines as they exist to-day. The dotted lines m,m, show the hills on either side of the valley as they existed during the process of filling, and the horizontal dotted lines r,s,t, the continuation of the beds a,6,c, before they were worn away. GOLD OR A VEL DEPOSITS. 279 Modern Forms. The carving of the country to its present form then began. The river waters on resum- ing their sway were diverted into new channels, and in most cases two streams were formed out of the orig- inal one. When lava Hows into a confined channel such as a valley, the surface and sides of the stream in contact with the rocks, and especiallj* the thinner edges, cool more rapidly than the central core, which, remaining in a plastic condition, is liable from the pressure behind to break the upper crust. This is consequently piled up in the center of the flow in rugged masses with a higher elevation than the sides. In this way there is formed a depression on each side of the flow next to the valley walls, each of which be- comes a watercourse, indicated by the arrows in fig. 1. Owing to the superior hardness of the lava the cutting away of the new channels took place largely at the expense of the rocks forming the walls of the valley. By degrees these were eaten away below the level of the under side of the lava, when the process went on more rapidly in the underlying clay and gravel, which on being undermined allowed the ^a to break off in vertical faces forming the characteristic bluffs of the gold regions. While this process was going on large quantities of the finer gravel of the original deposits were carried down to lower regions, taking with it the finest of the gold, the coarse remaining behind, and new placers were form- ing. We have evidence that there were two outbursts of lava, producing similar results. In the lower val- leys the lava caps are entirely basaltic, but in the higher regions the first eruptions were either trachytic or rhyolitic. Both eruptions are well shown in Plumas Co'unty, as in pi. 10, fig. 1. When, after the trachyte outburst, the cutting of the new valleys had proceeded to about half its ultimate extent, the basalt outbreak occurred and invaded some but not all of the streams. In this case the gravel contains pebbles of the lava c<>v- 280 PROSPECTING AND VALUING MINES. ering the older channel, a,&,c,(/, along with the quartz gravel which is characteristic of both, but the lava cap is au exceedingly hard, heavy, compact, black iron- like basalt, while the cap of the older channels is a light-colored gray or reddish trachyte, much lighter and coarser in grain than the basalt, and very harsh to the touch on a newly broken face. Being much softer than the basalt and less liable to take columnar forms, it seldom presents such conspicuous bluffs as the basalt. In some cases the basalt lies directly on the gravel; in others there is the usual bed of pipe- clay. If this is absent we may presume that the region was near the source of the lava flow, and that the material forming the clay bed had been washed down to the lower country or had not been ejected in large quantities. The clay beds under the basalt at Cherokee Flat in the foothills of the Sacramento valley are very thick, while in Onion valley, near the summit of the Sierra Nevada, at an altitude of 5,000 ft., they are either very thin or absent. That the eruption of the basalt was later than the formation of the older gravel beds is absolutely proved by the occurrence in the Laporte region, Plumas County, which is located on a trachyte-covered channel of great length and prominence, of a basalt cone overlying a bed of gravel, the pipe or neck of which was penetrated by one of the deep tunnels, and the gravel bed "drifted" all around it, some of the gravel being even surrounded by thin sheets of lava at the outer circumference of the neck which formed the vent. At this particular locality the trachyte cap had been eroded. The structure is shown in pi. 10, fig. 6, where a is the gravel and b the lava cone with its neck or pipe ascending through the bed- rock and gravel. Since the basalt outburst, which Was of enormous extent, covering hundreds or even thousands of square miles in California, Oregon and Washington, there seems to have been no serious volcanic disturbance, and GOLD GRAVEL DEPOSITS. 281 the denudation went steadily on up to modern times, leaving a mountain range in the case of each flow, of which we have a plan in pi. 11, fig. 1, which repre- sents two modern streams B,E, and the buried ancient river 8U, with those portions of its lateral streams which have not been worn away in the general denuda- tion. L represents the lava and pipeclay capping; G the gravel, and the heavy black lines that portion which is known as the bottom gravel and is suitable for drifting. As the denudation has not progressed evenly, it may happen that the gravel at some points has not been exposed, and the lava apparently lies on the bedrock, as at U. "Over/lows." In other places it may be exposed on ona or both sides of the ridge, or the lava cap may have entirely disappeared, as at (7, showing the gravel on the surface all the way across the dividing ridge. The richer bottom gravel found in the lateral branches of the stream will naturally be exposed as at T, T. A common term for these exposures is an "overflow," as though the gravel had been squeezed out of the hill, but that this expression is erroneous is shown from the fact chat the grade or inclination of the bedrock dips into the hill, as shown in pi. 10, fig. 5, where a is the so-called overflow and g the main channel to which it leads. The only exception to this rule is where a remnant of the head of one of these lateral branches is left on the other side of the modern ravine, which has cut the lateral in two without removing the upper portion. Unless this lateral was a large stream, the gravel left will be only a small patch. If a large stream it may present all the features of the main chan- nel if it happened to be covered with lava (which does not necessarily follow). Laterals. We also frequently hear miners speak of two or more channels in the hill. Such a condition of things is against all probability; the dividing of a stream into several branches being almost exclusively confined 282 PROSPECTING AND VALUING MINES. to those portions which have a flat grade, and does not occur where the grades are such as we find in mountain regions. What does occur is shown on the line OP, pi. 11, fig. 1, where if OP were a tunnel it would cut two bodies of gravel, but they would be only branches of the same stream, the first one encountered, if the tunnel started at 0, having a steeper grade than the second, as lateral branches of a river have almost universally heavier grades than the main river. If there is a sudden expansion of the lava cap, and a more than ordinary width between the rims, such a proposi- tion is almost sure to be found beneath the surface. PI. 10, fig. 2, represents such a structure as would be found on the line OP of pi. 11, fig. 1, where we have two gravel banks c,c, under one lava cap a. Without going into further detail it may be said that all these features can be reproduced in a model, thus proving the general accuracy of the theory of origin. Faulted Ancient Channels. It is not to be expected in a country which has been the seat of such compara- tively recent volcanic activity that there will be an absence of faults and dislocations in the channels. Un- fortunately these are numerous and often interfere with the successful working of otherwise valuable property. Three examples of such faulting are shown on pi. 11, in figs. 4, 5 and 6, all taken from the mining re- gions of Plumas and Sierra counties, Cal. Fig. 4 shows the situation at Grass Flat, near Laporte. Here the fault AB has cut the channel across its general direc- tion, the left hand portion in the figure having been raised, or the right hand portion depressed, as shown. The bedrock at e consequently acted as a dam, and backed up the water flowing down the bedrock, till it formed an underground reservoir P, the drainage outlet of which near A was so near the surface that grassy meadows were formed at C, sustained by the perennial water in P; hence the name. It was impos- sible to work the submerged ground until a long and expensive drain tunnel had been run. GOLD GRAVEL DEPOSITS. 283 Fig. 5, same plate, shows a fault running lengthwise of the channel in the pit at Laporte, ab being the dis- location, d the bedrock, c the gravel, and e gravel from the later series of gravels previously described, barren and almost entirely devoid of quartz bowlders. Such a fault is not so detrimental to the working of the de- posit, as it can be followed upstream without interfer- ence; but in such a case as in fig. 6, where the dikes c,c,c, have broken through and dislocated the gravel g, the drifting operations on the bottom gravels, shown in black, became so expensive that while the gravel was rich the expense involved in hunting the continuation of the channel beyond each dike consumed all the profits. Folded Gravel Beds. Instead of sharp faulting, gravel beds sometimes show evidence of disturbance in the shape of folds, either in smooth long sweeps or in a complication of smaller waves (pi. 12, figs. 1 and 2). Folds are, like faults, often accompaniments of volcanic eruptions, and the gravel may be dragged with the lava sheets. HILLSIDE DEPOSITS. These have the same origin as those just described, and are in fact in many cases, if not in all, only their lower portions, which, being at the time of the lava flows below the level of the sea or interior lakes, or for other causes, escaped the lava cap which buried the upper portions of the streams. As the land rose the streams began to cut down into these deposits, concentrating the contained gold on the bars and riffles along their sides, which sustain a constant renewal as the rainfall washes the hillsides down into the river bottoms. There is one class of hillside deposits, of local origin, in which part of the gold has, in descending, been con- centrated in pockets formed where favorable rock for- mations occur, as in the case of slates dipping into the hill. These pockets have since been covered over with soil and debris, and some of the gold may have bees 2S4 PROSPECTING AND VALUING MINES. carried out of them and further down the hillside, spreading out in fanlike shape. In searching for such pockets the prospector pans out samples of dirt along the foot of the hill, noting where pay or at least some gold begins and ends; then runs a corresponding line of pan tests parallel and higher up, marking the limits of the pay. If this second line is, as is probable, shorter, it will indicate a triangle near the apex of which the pocket is sought for by trenching. SEA BEACH DEPOSITS. These are mainly derived from ancient gravel beds, which are reconcentrated by being broken down by the impact of the waves, and sorted by the waves and tides. As these deposits are in most cases the furthest removed from their original source, the contained gold is of the very finest char- acter, and consequently the most difficult to save by mechanical appliances; these difficulties becoming steadily greater as the size of the particles of gold diminishes. If, however, the ocean were operating on solid rocks of any of the various kinds which contain gold, there is no reason why we should not find deposits of conglomerate with coarse gold, gradually fading out into finer and finer sediments with finer and finer gold, as the beds recede into deeper and deeper water, to which only the finer sediments would be carried by the reflux of the waves, or undertow. And further, if the coast line which is being destroyed be gradually sink- ing, as we know to be the case in many localities, just as it is rising in others, we should have such a bed of conglomerates, consisting of the larger waterworn frag- ments, extending over a large area, both in breadth and length, fading out on its upper surface into the finer and poorer material, and in some such way as this the beds of gold-bearing conglomerates may have been formed. The destruction of the shore line would be more rapid and the deposits more extensive than in those cases where the coast is gradually rising, as in this instance the same material would be longer exposed GOLD GRA VEL DEPOSITS. 285 to the abrading action of the waves, the formation of conglomerates would be less, and of fine sediments more extensive, and the gold particles would suffer more abrasion and be reduced in size. In searching for gold-bearing beach sands, these are naturally to be looked for under bluffs of gravel and conglomerate. A favorable time is after a strong wind blowing along the coast line, which makes cross waves, advantageous for concentration. The best spots will usually be those marked by lines and patches of black sand, which are almost alwa3 r s concentrated wherever any gold is. Besides the beach sands proper, gold-bearing sands have been worked, off-shore, by dredging, on the coast of New Zealand. GLACIAL DEPOSITS. Under this head are included all those deposits in which ice has played a part in their formation, and we have consequently evidences of more complicated action. As in all other deposits there must be, to start with, a belt of gold-bearing rocks to be removed, or the resulting mass will be barren. Given such a belt of rocks there is no reason why glacial deposits should not contain gold, just as those which have been derived from aerial erosion, but we are likely to find a greater variety in the physical ap- pearance of the gold, either smooth or angular, coarse or fine, because it has been released from the contain- ing rocks by a variety of methods. Glaciers transport to the lower valleys, first, the rocks or bowlders which are detached by frost from the exposed bluffs which form their boundary walls; and secondly, the rounded bowlders and sediment which are formed by their grinding action on the rocks over which they travel. If they cross a belt of gold-bearing rocks they must discharge into the valleys the contents of these rocks, along with the remains of the rocks themselves, either in the stream which issues from their "foot," or into the terminal moraine, if they 286 PROSPECTING AND VALUING MINES. terminate on land; or the contents may be widely dis- persed by floating ice or icebergs if they terminate in the water. While morainal deposits may be unsuited to min- ing ventures, the river deposits resulting from glacia- tion may be worked by machinery suitable to the re- tention of the excessively tine gold, which must neces- sarily be lost in the agitated waters of a sluice box. GRAVEL MINING. What Constitutes a Workable Gravel Proposition. The elements which go to make a workable gravel mine are : 1, the amount of and distribution of the gold in the gravel; 2, the width, continuity, and extent of the deposit; 3, the character of the bedrock; 4, the depth of the bedrock in relation to the neighboring ravines; 5, the grade of the channel or bedrock and freedom from faults; 6, the available dumping ground for the waste material ; 7, the character and amount of the water supply. While all these elements enter into every working proposition, they have widely varying values according to other conditions. Placer Mining. This term is sometimes used to in- clude all methods of working placers or gravel deposits; it is here applied in the usual and more restricted sense, excluding hydraulic mining (which involves the use of water under pressure) and covering only those methods of gravel washing (mainl.y in recent placers) in which the water depends for its working qualities simply on its quantity and the grade of the sluice boxes in which it is used. The altitude of the source of supply cuts no figure, except as it affects the grades on which the gravel can be washed. As this condition involves the handling of every pound of gravel by manual labor, or practically so, it is only the richer and consequently the shallower deposits which are available, such as the beds of ravines, river-bars and the shallower adjacent GOLD GRAVEL DEPOSITS. 287 deposits. When the former become too poor to work, the miner says he has lost the channel. It is not always meant that there is no longer indication of gold, but its concentration is not sufficient to warrant hand- ling by such slow methods. For the "pan" and the "rocker" a very small quantity of water may be suffi- cient, and the amount of material handled daily is so comparatively small that the question of dumping ground does not trouble the miner, neither does the grade of the channel, nor disturbance by faults, be- cause his appliances are movable on short notice; and the same may be said of the "long torn" or sluice box into which the gravel is shoveled when working on a somewhat larger scale; but the depth and character of the bedrock may be all important, as it is on the bed- rock that the miner finds his chief reward. If he is unable to reach it on account of the influx of water, the cost of wing-damming the stream or pumping may eat up all the profits, and after all the bedrock may be such that it has not been able to retain the gold. A perfectly smooth sluice box would permit all the gold to escape, and to avoid this the bottom is either provided with riffles in the shape of slats, or paved with bowlders and sometimes with wooden blocks cut across the grain. All of these methods provide crevices into which the gold drops as it is swept through the boxes by the force of the w j ater, and is thus prevented from escaping. The bedrock in a stream acts in the same way. If perfectly smooth, as at E, pi. 12, tig. 3, it may be absolute!} 7 clean, there being no obstruction to give anything a retentive hold. A case of this kind occurred at Gibsonville, Cal., where a long tunnel was run to open a piece of ground lying between two mines which had paid handsomely, only to find on reaching the channel a perfectly smooth bedrock and almost perfectly barren. The most favorable condition is a bedrock pitching down stream as at A, in the same diagram, so that all the crevices are presented to the 388 PROSPECTING AND VALUING MINES. impact of the descending material. In such crevices the gold is literally jammed into the rock, and it will usually pay to mine from 6 in. to 1 ft. of its surface .ilong with the gravel, especially if it be softer, as the miners say, "cheesy." A similarly good bedrock is formed by the worn surfaces of limestone B and (7, which being eaten out into irregular holes act as per- fect riffles and give good results, as at Shaw's Flat and Columbia, Cal. ; but less satisfactory returns are usualb' had from slaty rocks pitching up stream as at D, especially if the rocks be hard, as objects slip readily over such surfaces. The application of these principles will soon enable the prospector to work out the problems for himself and test his theoretical knowl- edge by experience. "Potholes," which are smooth round pits worn in the solid rock by the constant fall of water charged with sand, or the grinding action of an imprisoned bowlder, like a pestle in a mortar, are apt to be swept clean of any valuable contents. Bowlders in the bed of the stream of course act as riffles, but when large they add materially to the cost of mining, requiring derricks for their removal and much extra labor. If the gravel is cemented, as is not infrequently the case, it may be necessary to leave it exposed to the air to slack, if the cementing material (as clay) is such as will yield to such simple treat- ment; or it may be even necessary to pass it through a stamp mill; but deposits of this character are not likely to attract the placer miner, as they involve the outlay of considerable capital, which is only warranted by extensive explorations and the proof of extensive deposits. Gold Pan. Prospecting is usually done with a large shallow iron pan about 16 in. or more in diameter across the top, by 2| in. deep, with flaring sides, stamped out of a single piece of charcoal sheet iron, called and well known as a "gold pan." Such a pan filled with gravel and fairly heaped in the center will GOLD GRAVEL DEPOSITS. 289 hold about 25 Ib. and about 150 pans are usually con- sidered equal to a cubic yard (the number varies with the size of the pan); values of gravel being estimated either by the pan or by the cubic yard and not by the ton. A cent is a piece of gold about -^ in. square and half as thick as a $5 piece, as an approximation to give some comparative idea of size and value. With these figures the prospector can form some idea of what he may be able to do daily, as soon as he has found out how many pans of dirt he can wash daily or how many yards of gravel he can shovel into a sluice box, both of which will vary according to the locality, the character of the ground and the dis- tance to water. Persistent panning is the only thing which will test a gulch. Just as one swallow does not make a summer, one pan of good dirt does not make a mine; nor does the failure to find gold in the first pan prove the locality to be barren. As a usual thing an abundance of quartz pebbles in the gravel is a good indication, and when these are accompanied with an abundance of black sand, minute garnets (transparent and red) and small rounded shot-like pebbles of chrome iron, it is not well to be easily discouraged. The signs of course may fail, but they are what the Mexicans term pintas or colors, and call for a thorough search. If the deposits are too poor to be worked by these primitive methods, but are shown to carry gold (as proved by extensive panning) over a large and well defined area, we may resort to the methods employed in Hydraulic mining, by which we can move and wash per man so vastly an increased quantity of gravel, that ground very poor in its average contents may prove remunerative ; but we must remember that the hydraulic miner always calculates on a rich bottom streak which has to bear the loss, if any, involved in removing the top dirt, which may sometimes be a valueless clay; and generally stops work on the bank when the limits of this bottom streak are reached laterally 290 PROSPECTING AND VALUING MINES. By hydraulic mining we understand the use of water under pressure; that is to sa3 r , at some suitable point the stream is turned into pipes which convey it to the ground to be worked ; and by this means we take advan- tage of the weight of the water in the pipes to force large quantities through a nozzle, and secure a power to cut away the gravel bank without the aid of pick or shovel, and wash the material into suitable sluices. According to the pressure or head and the amount of water used, a miner's inch of water* will wash from 3 to-10 cu. yd. of gravel. The "head" is the differ- ence in height between the point at which the water enters the pipe and that from which it is discharged; while the "pressure" is equal to the weight of a column of water of this height multiplied by the cross sectional area of the pipe, both in feet, by the weight of 1 cu. ft. of water, from which must be deducted the loss caused by friction (called the friction head) against the sides of the pipe, which will be governed by its length, size and condition of its interior as regards smoothness and cleanliness. This loss is greatest in small pipes. It is evident that the grade of the gravel to be worked will depend on the number of yards which can be moved daily by a given quantity of water, and that this will depend on the pressure under which the water is used. To increase this pressure we have to gain altitude, and this forces the head of the water supply further and further back into the mountains; and as this supply must be constant during time of rain and drought alike, we are compelled to build reservoirs, into which the various minor sources of supply are collected and held in reserve. When we remember that mines such as those at North Bloom field and Cherokee Flat, using 2,000 miner's inches or over, consume daily more than 33,000,000 gal., or water sufficient for a city * 2,230 cu. ft. a tank 12x12x15 ft. (See Chapter XVII. on Water.) GOLD GRA VEL DEPOSITS. 291 of 350,000 inhabitants, it is not to be wondered at that there must sometimes be an expenditure of $400,000 or $500,000 on the water plant before a yard of gravel can be washed. With such a heavy preliminary ex- penditure on water, besides the cost of tunnels, sluices, buildings, etc., at the mine, annual repairs and working expenses, we must have correspondingly large deposits of gravel to justify the enterprise. The North Bloomfield Company in 1879 used 931,000 miner's inches of water (15,000,000,000 gal.), each inch of which moved on an average about 4 cu. -yds. of gravel, or a total of about 3,724,000 cu. yds., equal to 2,310 acres 1 ft. thick, 231 acres 10 ft. thick or 23 acres 100 ft. thick. The actual area removed was prob- ably about 7 acres some 300 ft. in depth. These are of course outside figures, but they emphasize very strongly the necessity of a thorough inspection of the water supply, and the facilities for disposing of or im- pounding the debris, before opening an extensive hydraulic proposition. It is time enough to test the quality of the bank when the water and debris ques- tions are settled. It would be beyond the proper scope and purpose of the present work to enter into the details of this highly developed method of mining. For such infor- mation the reader is referred to "A Practical Treatise on Hydraulic Mining in California, " by Augustus J. Bowie, Jr.; "Practical Notes on Hydraulic Mining," by Geo. H. Evans; "Manual of Hydraulic Mining for the Use of the Practical Miner, " by Theo. F. Van Wagenen, and other books and current literature. Drift Mining.- There are, however, large bodies of gravel which cannot be handled by purely hydraulic methods for one or other of the following reasons: (1) The water supply may be totally inadequate, or the deposit may not justify the expense of bringing it on the ground; (2) the dumping ground also may be in- adequate, or local interests may prevent it from being 292 PROSPECTING AND VALUING MINES. made available; (3) the' top dirt may be so thick and worthless as not to warrant its removal ; (4) the de- posit may be entirely capped with lava, which cannot be economically removed; (5) the ravines on either side of the ridge containing the channel may not have been cut down deep enough to enable us to put in a tunnel on a hydraulic grade, or they may be too flat for suitable washing sluices; or (6) the ravines may be so high that their bottom is above that of the old chan- nel, as in pi. 10, fig. 3, and we cannot gain access by a tunnel under any conditions. In this last case it will be necessary to work the mine with pumping machinery through either shaft or in- cline, of which latter method the successful Damascus mine in California is a good example; but in this in- stance the incline followed the channel on its descend- ing grade, and did not involve the dead work of shaft- ing, the use of which cannot be said to have been more than partially successful. In all the other cases bed- rock tunnels are resorted to, which are run through the rim on a water grade until the channel is reached, when the gravel is extracted and handled in cars very much in the same way as a coal mine is operated. Water can be accumulated until sufficient gravel is taken from the mine, and a clean up can be made daily, weekly or monthly as the case may be. Having to wash so small a quantity of gravel, comparatively speaking, the sluice boxes may be small, and but little water is required under very slight pressure or none at all, so that the plant is not necessarily costly. Given the gravel, the success of drift mining depends on the location of the tunnel with regard to the bottom of the channel, for many months of labor and many thousands of dollars may be expended on a tunnel which may be valueless if it should unluckily enter the gravel above the bottom of the channel, which it is unable to drain and render workable, as is the case with the lower tunnel in pi. 11, fig. 2. It is infinitely better to be GOLD GRAVEL DEPOSITS. 293 too low than too high, but the location of these tunnels is a problem which will severely task the engineer and geologist combined. The greater number of the drift mines are located well up in the mountains, on the steeper grades near the head of the old channels, and it is only here and there that the shape of the country has caused the re- moval of the lava cap and exposed the underlying gravel in such a shape that hydraulic work was pos- sible, so that long stretches of the ancient river lie be- tween these isolated spots where the altitude of the bedrock has been ascertained. In these unexplored sections it is only by inference that we know the chan- nel to exist, and numberless abandoned tunnels show how little the miners were acquainted with its struc- ture. To open a mine in such a situation is a delicate task and can only be safely done after boring across the general line of the old river, to ascertain the true position of its deepest portions, and its depth from the present surface. But before this can be done we must determine the course of the old stream so that we may be sure that the bore holes are located across, and do not follow it lengthwise. To make certain of this the rim of the channel on each side of the ridge must be carefully traced out and platted as in pi. 11, fig. 1, noting where the lava, pipeclay or gravel shows in contact with it; and the survey should be extended to include the bed of the ravines on each side of the ridge ; levels should be run the entire length of the rim and the creek bottoms, with full notes of the rocks exposed in the latter, and these levels will disclose the exposed ends o.f the lateral streams T, T, which will outcrop in the lowest parts of the rim. When such a survey is platted we can approximately draw in the center line of the main channel, and of its branches, on the plan; which will cover only the main stream where its rims are approximately parallel, or the main stream and a lateral if there are wide expansions as at OP, and an 294 PROSPECTING AND VALUING MINKS. exposure as at /. From these data we can draw an approximate cross section at any point, such as pi. 10, fig. 4, in which the rims are at the same altitude, making the unseen slopes of the old river af and gf, the same as those visible between the rim a and the bed of the creek h. It is evident that under such condi- tions the length of a horizontal tunnel to tap the bottom /would be equal to the width of the channel between the rims a g, as the triangles dca, abf and fbg are all similar. More difficulty will attend the determination of the length on such a line as OP, pi. 11, fig. 1, but the solution is practicable as an approximation. Of course this is not an absolute method, as it is based on the probability of the same rock taking the same or practically the same slopes when worn away under similar conditions, and this maj r not ahvays be the case; but it will do to determine whether a tunnel is feasible, as, if the distance to the creek, as from e to h, is less than one-half the width between the rims, the probabilities are altogether in favor of the condi- tions shown in pi. 10, fig. 3. If the rims are of differ- ent altitudes, as in fig. 3, the center of the old channel will probably be located proportionately nearer the lower rim. If this preliminary test prove satisfactory we can locate the borings with certainty, and they should be not less than three in number, probably five or up- wards, as their respective depths may indicate. To ascertain the probable grades of the channel we must extend our investigations to the beds of the creeks on each side of the ridge, as it is important to know be- forehand whether the country is faulted, whether the channel is choked by bowlders, and whether we are likely to encounter flat, moderate or steep grades in the ground when opened, as bad faulting might lead to failure, and might not be disclosed by the borings; bowlders are more difficult to handle even than in the open air; and the grades, as we have seen, largely in- QOLD GRAVEL DEPOSITS. 295 fluence the amount of gold in the bedrock gravel. There will probabb r be under any circumstances a slight flattening at the junction of each lateral branch with the main stream. By examining the modern ravines we may possibly find in each a band of rock as F, pi. 11, fig. 1, which is easily recognizable, and by using this as a common base, and following each ravine both up and down with a line of levels, we can arrive at a very fair idea of the probabilities where we cannot see the bed of the channel from what is visible in those of modern origin, especially if we find the rock strata occurring in orderly succession in each stream, on all points on which we desire information, whether it be faulting, dip of the rocks, accumulation of bowlders or grade. It would be possible to enlarge on this theme almost indefinitely, but enough has been said to furnish the key to the methods of exploration, which must be varied to suit each particular locality; and the miner, by the aid of this key, can study for himself the chances of success. The boiing is not difficult or ex- pensive, and will be nearly as satisfactory as an open shaft, which will cost more, take more time to sink, and might not after all be suitably located. The trachytic lavas seem to abound in choke-damp or car- bonic acid gas, making good ventilation in the shafts imperative. Machine Washing. The operations just spoken of are based on the use of large quantities of water in open sluice boxes, in which there must inevitably be a loss of fine gold, as the records of the undercurrents show. Workings on a large scale have demonstrated the presence in gravel of gold so fine that it is not visible in the pan to the naked eye, just as reasoning demonstrated should be the case in gravels which owe their origin to glacial action, or which contain the products of the decomposition of pyrites. This very fine gold must certainly be swept away in the swirl of such streams as are used in either hydraulic or drift 296 PROSPECTING AND VALUING MINES. operations, as it takes a long time to settle even in still water. To save such gold it must be brought into contact with quicksilver in such a way that it cannot escape amalgamation. Such is the intention of all mechanical appliances which have been proposed. It is sufficient to say that by their means gold has been saved which is so infinitely fine that it can be applied as a paint on paper, producing a gilding smoother and thinner than gold leaf. Its presence having been demonstrated, the apparent absence of gold in the de- bris from localities where auriferous pyrites have been largely denuded is explained, and the metal is probably much more widely disseminated than has heretofore been supposed. The discovery of gold in this condi- tion and the ability to save it may have far-reaching results in gold mining, especially as in talcose rocks and serpentines much fine gold occurs as films of in- finitesimal thinness, which increase the value of the assays, but is exceedingly difficult to save in the mill. In a piece of solid rock we have the material con- trolled, no matter how fine it may be, and can detect its presence by assay of even small samples, but unfor- tunately we have no way of concentrating gravel so as to get suitable assay samples except by laborious processes, and may have to depend on working tests for the detection of such gold. Test for Fine Gold in Gravel. Probably the best ex- perimental method would be to wash a large quantity of gravel, previously measured, in the same water, never allowing any of the latter to escape, but using it over and over again, retaining only the finest sands by a proper system of screens; and when a suitable quantity of sands had been accumulated they might be treated by the chlorination process, which dissolves every trace of fine gold in the mass and saves nearly all of it. The result obtained divided by the number of yards of gravel concentrated would give the average value per yard, and this might be greatly GOLD GRAVEL DEPOSITS. 297 more than shown by test workings in the sluice box. The difference between the two results would be the invisible gold. All machines suitable for this class of work use much less water per yard of gravel washed than is necessary in hydraulic operations, and this is a most important item if the deposits are so situated that pumping mast be resorted to, as a good head of water (pumped) will cost from 15 to 30 cents per miner's inch according to the height to which it must be raised, and the length of the pipe through which it has to be forced, or the cost of labor and fuel. Dry Washing. The difficulties attending the sepa- ration of gold without the use of water, or as it is called rather curiously, "dry washing," are enormous, and it can only be attempted on the richest kind of material with even a shadow of success. The great mistake is made, as in so many other mining machines and processes, originated by persons who as a usual thing are totally ignorant of what has been attempted by others before they became inoculated with the idea, of supposing that the careful manipulation to which the inventor subjects the small quantity of material on which he operates can be repeated on a large scale in actual mining. For success it is absolutely necessary that the material should be absolutely dry and thor- oughly pulverized, as any moisture, especially in clayey soils, will prevent the grains of gold from separating from the earthy matter. Hydraulic Elevators. -Not a few localities in which gold is found abundantly present difficulties due to insufficient room below the deposit, on which we can construct sluices of sufficient length to properly wash the gravel, and in which we can deposit the debris after it is washed. In such cases we are com- pelled to resort to hydraulic elevators, by which the gravel is lifted from 30 to 50 ft. or over and there dumped into the sluice boxes, which can then be from 29S PROSPECTING AND VALUING MINES. one-eighth to a quarter of a mile longer than would otherwise be possible. The method is of course only available on moderately coarse material, as the diame- ter of the tube and the force of the lifting jet prevent the passage of very coarse material. River Bars. These usually form at the junction of two streams, or just below the point at which the cur- rent is deflected from one side of the river to another. If a stream is auriferous, these bars are often rich in gold, which is brought down in flood time from the upper country, often many miles. The Snake, Colum- bia and Fraser Rivers are good examples of such streams, in addition to the well known California localities. On the Fraser, at Yale, the amount of fine gold brought down by the stream, to localities not less than 50 miles from the source of supply, is so great that the surface of the pebbly bars, which act as riffles, pays to work over annually; and a panful of moss gathered from the bowlders exposed between high and lo\v water mark, will show from fifty to several hun- dred colors. It can easily be understood from this that bars which have remained untouched for years may therefore be very rich; immensely so in some in- stances. Hill's bar, below "Yale, must have yielded many dollars per cubic yard, when seven men with three rockers took out $90,000 in 90 days. These bars may be so near the level of the water, that it inter- feres materially with working them. In such cases Wing dams are resorted to. These structures consist of a wall of brush and bowlders, built out in the shallow water at some suitable point above the ground to be worked, to divert the current and inclose a block of desirable ground. The current is used to run water wheels which pump the inclosure dry or sufficiently so to enable the working of the gravel to be successfully carried on. Such structures are of course only available during a low stage of water, and sudden flood is apt to wash them away, making GOLD GRA VEL DEPOSITS. 299 the operation risky, as a whole season's work, as well as the money invested, may be lost in an hour. In some few cases ifc may be possible to divert the stream, which is a more satisfactory method if the ground rendered available is sufficiently extensive to justify the expense. Probably one of the most successful enterprises of this kind was on the Cape claim near Oroville, in California, the owners of which in early days turned the Feather River into a flume 40 ft. wide, and cleaned up from $600,000 to $700,000 in one summer's work, although they lost the flume during a sudden freshet before the job was completely finished. Dredging the bed of the stream is sometimes resorted to, it being reasonable to suppose, from all we know of gravel mining, that if the bars in a river are worth working, the gravel beneath the surface, which we cannot see, must also contain gold in paying quan- tities. Such dredges are in successful operation in several localities, both in America and elsewhere. Some machines can handle as much as 150 tons of gravel an hour; but the quantity, as well as the suc- cess of the dredge, will depend largely on the character of the river bottom. If it is encumbered with large bowlders, it may be impossible to work it to advan- tage, and the best results will be obtained in moder- ately fine material of a uniform character. Adjustment of Saving Appliances to the Size of the Gold. In any appliance for working gravel by water, the measure of success will largely depend on the careful adjustment of the amount of water used, and the grade of the tables or sluice boxes, on or in which the gravel is washed, to the size of the particles of gold in the material under treatment; and the finer and finer these become the more accurate must be the adjustment. There are many localities where the entire bulk of the gold is so fine that we have to resort to the use of the principles involved in the undercurrent, or to the use of amalgamated plates, or to a lining in the 300 PROSPECTING AND VALUING MINES. sluice box, made of inch boards bored full of holes, or to blankets, burlaps, or rawhides with the hair point- ing up stream, as in China; or to cocoanut matting laid over a coarse linen cloth, as in New Zealand. The localities where this kind of gold is chiefly found are along the banks of large rivers and sea beaches, and the gold is frequently accompanied by such large quantities of "black sand" (consisting of magnetic and titaniferous iron derived from the decay of granitic rocks) that these, in any stream weak enough to save the flaky gold, choke the saving appliances with a solid bed of iron sand, through which it is impossible for the gold to sink and reach the riffles or quick- silvered surface below, and it is consequently passed on through the sluices, on the top of the sand. The only method of improving this state of affairs is to first extract the iron sand, or that portion of it which is magnetic, from the material under treatment, so that the remainder may be finished in a much gentler cur- rent than would be necessary to carry off the iron sand, and yet sufficient for the task of separating the quartz sands from the gold. Various appliances have been designed to work these sands, but until recently they have met with but a very limited share of suc- cess. There appears, however, now to be a prospect, by the use of magneto-electrical appliances, of making more progress in the solution of the problem, which is a fascinating one on account of the abundance and widespread area of the material, and its constant restoration by the operations of nature. In working this class of material, the aim should be to make the machinery as light and portable as possi- ble, so that it may be readily moved to the material instead of hauling the material to the machine, as this rapidly becomes an expensive process, for while the material may be abundant it is usually of no great thickness at any one point. This is particularly the case in beach sands, which may be scattered by heavy GOLD GRAVEL DEPOSITS. 301 storms and afterward reasserted by the gentler action of the waves in more moderate weather, which pan out the lighter particles of sand, leaving the gold and iron in a concentrated form. Throughout this chapter especial attention has been paid to gold, but the same principles of prospecting and working are equally applicable to all minerals found in similar conditions, such as tin, platinum and its allies, and even native silver as at Planchas de Plata, in southern Arizona. These metals are, how- ever, all worked in open air placers, and have not yet been found, so far as the writer is aware, in paying quantities in drift operations, though platinum and iridosmine are found in nearly all the gravel diggings of California, along with occasional diamonds. CHAPTER XVII. WATER AND ITS MEASUREMENT. WATER plays so important a part in all mining operations that the available supply becomes a vital question, whether for gold washing, for power or for milling and domestic use. The following simple rules for ascertaining the quantity and estimating the power which can be derived from it will be found useful in this connection. Unit. Water may be measured by the gallon, the cubic foot or the miner's inch, and the use of the special term depends somewhat on the purpose to which the water is to be applied; thus, city supplies are usually estimated in gallons; irrigation quantities in cubic feet or miner's inches, and for mining opera- tions on a large scale almost universally in inches. Weight. A cubic foot of fresh water, with the barometer at 30 in., weighs, at 39 F., 62.423 Ib. ; 62.367 Ib. at 60; 62.218 Ib. at 90; and only 59.7 Ib. at 212, a fair average being 62.33 Ib., but usually called 62.51b. for convenience. Below 39 the weight decreases, so that at 32, or the freezing point, it is only 57.2 Ib. and its specific gravity only 0.9195. Sea water weighs from 64.02 to 64.27 Ib. per cu. ft. Bulk. 'A gallon of water U. S. standard contains 231 cu. in. This is equal to a cylinder 7 in. high by 6 in. in diameter, or to a cube 6.1358 in. on the edge, and is 0.13368 of 1 cu. ft., so that 1 cu. ft. contains 7.48 gal., or in general terms 1\ gal. Miner's Inch. This is the quantity of water which WATER AND ITS MEASUREMENT. 303 will flow through an orifice in a 1-in. board, 1 in. sq., in 24 hours. In selling water, however, the water companies sometimes make rates by the 10-hour and 12 hour in., users not requiring it for the full 24 hours. The inch varies according to the pressure under which it is discharged. The term arose in California in the early days of gold mining, but the customs of differ- ent camps varied, as the "head/* by which is meant the distance from the top of the water to the center of the hole, ranged from 4 to 7, or sometimes as much as 8 in. The 4-in. head is still used in the irrigation districts of southern California, but the 6-in. head has of late years been considered the standard in mining estimates. Under a 4-in. head, through an orifice 1 in. sq., the discharge is equal to 1,728 cu. ft. or 12,- 925 gal. in 24 hours. The 6-in. head discharges about 2,150 cu. ft., or 16,082 gal. in the same time. The North Bloornfield reports, as the results of experi- ments by Hamilton Smith, give 2,230 cu. ft. or 16.680 gal. The measurement is made by leading the water into a tank, provided at a height of 2 in. from the bot- tom with a horizontal slot of given dimensions, say 2 in., which can be closed by a moving bar, sliding in it. If it is desired to measure all the water, this bar is slid back until it allows the water to escape at such a rate that the surface stands constantly at the re- quired head, and the size of the aperture can be read off immediately by graduations on the bar. If the slot is 2 in. high and the bar has been slid back 60 in. the flow will equal 2 X 60 = 120 in. If it is desired to measure off a definite quantity the slot or gate is properly adjusted, and the waste gate opened until the requisite head is obtained in the measuring tank. Pressure. Water exerts the same pressure in all directions. In pipes the pressure is equal to the area of the pipe in feet, multiplied by the vertical height of the pipe (not by its length), and the quantity thus Ascertained by 62^ lb, (the weight of 1 cu. ft. of 304 PROSPECTING AND VALUING MINES. water), or, if the area is calculated in inches, by 0.432292 of a pound (the weight of a column of water 1 in. sq. and 1 ft. high), and this by the height ver- tically of the pipe in feet, the result will be the pres- sure per inch in pounds. Moving water exerts less pressure than when it is stationary, but when cut off suddenly puts a greater strain on the pipe than the simple stationary load, to which the momentum of the moving column has been added. The following table (condensed from Trautwine) gives the weight of water, at 62 Ib. per cu. ft., con- tained in 1 ft. of pipe of different diameters from 1 to 36 in. The fractions of inches are omitted, as seldom us^d in mining operations. WEIGHT OF WATER IN 1 FT. OF PIPE. Diam. in Inches. Weight, Lb. Diam. in Inches. Weight, Lb. Diam. in. Inches. Weight, Lb. Diam. in Inches. Weight, Lb. 1 0.33952 10 33.952 19 122.56 28 266.18 2 1.3581 11 41.082 20 135.81 29 285.53 3 3.0557 12 48.891 21 149.73 30 305.57 4 5.4323 13 57.379 22 164.33 31 326.27 5 8.4880 14 66.545 23 179.60 32 347.66 6 12.223 15 76.392 24 195.56 33 369.74 7 16.636 16 86.916 25 212.20 34 392.48 8 21.729 17 98.121 26 229.51 35 415.90 9 27.501 18 110.000 27 247.51 36 440.00 The quantities increase as the squares of the diame- ter of the pipes. Thus a 36-in. pipe contains four times as much as one 18 in. in diameter 440 to 110. Discharge Under Head. The discharge of a pipe from the bottom of a reservoir is found by multiply- ing the area of the orifice by the velocity of the stream, which depends upon the head or pressure. If the opening is circular multiply the square of the diameter in feet or inches by 0.7854, and this will be the area in feet or inches. The velocity of discharge is ascertained by multiplying the square root of the bead in feet by 8,03, and the result will be the veloc- WATER AND ITS MEASUREMENT. 305 ity in feet per second. The following table (con- densed from Trautwine) gives the velocity of dis- charge in feet per second for heads of from 50 to 500 ft. Intermediate heads can be made proportional to the nearest figures: VELOCITY OF DISCHARGE UNDER DIFFERENT HEADS. Head. Velocity Per Second. Head. Velocity Per Second. 50 56.7 125 89.7 55 59.5 150 98.3 60 62.1 175 106.0 65 64.7 200 114.0 70 67.1 225 120.0 75 69.5 250 126.0 80 71.8 275 133.0 85 74.0 300 139.0 90 76.1 350 150.0 95 78.2 400 160.0 100 80.3 500 179.0 Power of Falling Water, (on the assumption that one horse power is equal to 33,000 Ib. raised 1 ft. per minute). Multiply together the number of cubic feet of water which fall per minute; the vertical height of the fall or head in feet; and the number 62.3 (the weight of 1 cu. ft. of water in pounds) ; and divide the result by 33,000. Thus 800 cu. ft. of water falling 16 ft. would give a theoretical horse power of 24.17. But water wheels do not realize all this power. Undershot wheels only realize from one-quarter to one-third; breast wheels about one-half; overshots, from two- thirds to three-quarters; turbines and wheels of the Pelton type from three-quarters to 85%. In general terms large quantities of water under small heads are best utilized by turbines; but above 20-ft. heads the impact wheel will be found satisfactory even up to pressures of 2,000 ft. The makers of the Pelton wheel issue a circular giving useful data in relation to the measurement and use of water, and from it the follow- ing tables are extracted. The first gives the b. p. of 306 PROSPECTING- AND VALUING MINES. 1 in. of water under heads from 1 up to 1,100 ft. This inch equals 1| cu. ft. per minute. The table assumes 85% efficiency. TABLE FOR CALCULATING HORSE POWER. Heads in Ft. Horse Power. Heads in Ft. Horse Power. Heads in Ft. Horse Power. Heads in Ft. Horse Power. 1 0.0024147 320 0.772704 170 0.410499 480 .159056 20 0.0482294 330 0.796851 180 0.434646 490 .183206 30 0.072441 340 0.820998 190 0.458793 500 .207-350 40 0.096588 350 0.845145 200 0.482940 520 .255644 50 0.120735 360 0.869292 210 0.5071/87 540 .303938 60 0.144882 370 0.893439 220 0.531234 560 .352232 70 C. 169029 380 0.917586 230 0.555381 580 .400526 80 0.193176 390 0.941733 240 0.579528 600 .448820 90 0.217323 400 0.965880 250 0.603675 650 .569555 100 0.24147'0 410 0.990027 260 0.627822 700 .690290 110 0.265617 420 .014174 270 0.651969 750 .811025 120 0.289764 430 .038321 280 0.676116 800 1.931760 130 0.313911 440 .062468 290 0.700263 900 2.173230 140 0.338058 450 .086615 300 0.724410 1000 2.414700 150 0.362205 460 .110762 310 0.748557 1100 2.656170 160 0.386352 470 .134909 Measurement by Weirs. In general terms a weir is any obstruction across a stream, as a dam, over which all the water in the stream is compelled to flow, or so much of it as may be desired, which can be regulated by suitable waste gates, which will maintain a constant depth on the weir. Select a place in the stream, where on being dammed a pond will be formed of sufficient length to check the velocity of the stream. Across the lower end of this spot place a board or plank, in which a square notch has been previously cut through which the water must flow. The length of the notch in the dam should be from two to four times its depth for small quantities of water, and longer for large quantities. The edges of the notch should be beveled toward the intake or upper side, and the clear fall below the notch should be not less than twice the depth, that is 12 in. if the notch is 6 in. deep, and so on, to prevent loss by back water. In the pond, from 3 to 6 ft, above the dam, according as WATER AND ITS MEASUREMENT. 30? the stream is small or large, drive a stake, and then obstruct the water until it rises precisely to the bot- tom of the notch (which must be level) and mark the stake at this level. Then complete the dam so as to cause all the water to flow through the notch, and after allowing time for the water to settle, mark the stake again for this new level. If preferred the stake can be driven with its top precisely level with the bottom of the notch and the depth of water be measured with a rule after the water is flowing freely through the notch, but the marks are preferable in most cases. The distance between the marks is the theoretical depth of flow corresponding to the depth in the table, where an example is given of the method of making the calculation. The quantity thus obtained can be converted into gallons or miner's inches as desired. The following table will save trouble in making com- putations from weir measurements : TABLE FOR WEIR MEASUREMENT. Giving cubic feet of water per minute that will flow over a weir 1 in. wide and from y% to 20% in. deep. Inches. M M % Yz % H % .00 .40 1.13 2.07 3.20 4.47 5.87 7.40 9.05 10.80 12.64 14.59 16.62 18.74 20.95 23.23 25.60 28.03 30.54 33.12 35,77 .01 .47 1.23 2.21 3.35 4.64 6.06 7.60 9.26 11.02 12.88 14.84 16. 83 19.01 21.23 23.52 25.90 28.34 30.86 33.45 36.11 .05 .55 1.35 2.34 3.50 4.81 6.25 7.80 9.47 11.25 13.12 15.09 17.15 19.29 21.51 23.82 26.20 28.65 31.18 33.78 36.45 .09 .64 1.46 2.48 3.66 4.98 6.44 8.01 9.69 11.48 13.36 15.34 17.41 19.56 21.80 24.11 26.50 28.97 31.50 34.11 36.78 .14 .73 1.58 2.61 3.81 5.15 6.62 8.21 9.91 11.71 13.60 15.59 17.67 19.84 22.08 24.40 26.80 29.28 31.82 34.44 37.12 .19 .82 1.70 2.76 3.97 5.33 6.82 8.42 10.13 11.94 13.85 15.85 17.94 20.11 22.37 24.70 27.11 29.59 32.15 34.77 37.46 .26 .92 1.82 2.90 4.14 5.51 7.01 8.63 10.35 12.17 14.09 16.11 18.21 20.39 22.65 25.00 27.42 29.91 32.47 35.10 37.80 .32 1.02 1.95 3.05 4.30 5.69 7.21 8.83 10.57 12.41 14.34 16.36 18.47 20.67 22.94 25.30 27.72 30.22 32.80 35.44 38.15 1 2 3 4 5........ 6 7 ,. g 9 10 11 12 13 14 .. 15 16. 17 18 19 20 308 PROSPECTING AND VALUING MINES. Suppose the weir to be 66 in. long, and the depth of water on it to be 11| in. Follow down the left hand column of the figures in the table until you come to 11 in. Then run across the table on a line with the 11, until under f on top line and you will find 15.85. This multiplied by 66, the length of weir, gives 1046.10, the number of cubic feet of water passing per minute. Measurement in an Open Stream by Velocity and Cross Section. Measure the depth of the water at from 6 to 12 points across the stream at equal dis- tances between. Add all the depths in feet together and divide by the number of measurements made; this will be the average depth of the stream, which multiplied by its width will give its area or cross section. Multiply this by the velocity of the stream in feet per minute, and you will have the cubic feet per minute of the stream. The velocity of the stream can be found by laying off 100 ft. on the bank and throwing a float into it at the middle, noting the time passing over the 100 ft. Do this a number of times and take the average. Then dividing this distance by the time gives the velocity in feet per minute at the surface. As the top of the stream flows faster than the bottom or sides the difference being about 8% it is better to measure a distance of 120 ft. for float and reckon it as 100. This method can also be applied to measurements of water in flumes. The error will tend toward excess, if the friction along the sides and bottom is not allowed for. WATER AND ITS MEASUREMENT. 309 TABLE FOR MEASURING WATER BY MINER'S INCHES. Length of Opening in Inches. Openings 2 Inches High. Openings 4 Inches High. Head to Center 5 in. Head to Center 6 in. Head to Center 7 in. Head to Center 5 in. Head to Center 6 in. Head to Center 7 in. 4 . Cu. Ft, 1.348 1.355 1.359 1 361 Cu. Ft. 1.473 1.480 1.484 1.485 1.487 1.488 1.489 1.489 1.490 1.490 1.490 1.490 1.491 1.491 1.492 1.493 1.493 1.493 1.493 1.493 1.494 Cu. Ft. 1.589 1.596 1.600 1.602 1.604 1.604 1.605 1.606 1.606 1.607 1.607 1.607 1.607 1.608 1.608 1.609 1.609 1.609 1.609 1.610 1.610 Cu. Ft. 1.320 1.336 1.344 1 349 1.352 1.354 1.356 1.357 1.359 1.359 1.360 1.361 1.361 1.362 1.363 1.364 1.365 1.365 1.366 1.366 1.366 Cu. Ft. 1.450 1.470 1.481 1.487 1.491 1.494 1.496 1.498 1.499 1.500 1.501 1.502 1.503 1.503 1.505 1.507 1.508 1.508 1.509 1.509 1.509 Cu. Ft. 1.570 1.595 .608 .615 .620 .623 .626 .628 1.630 1.631 1.632 1.633 1.634 1.635 1.637 1.639 1.640 1.641 1.641 1.641 1.642 6 8 10 12 1.363 1.364 1.365 1.365 1.365 1.366 1.366 1.366 1.367 1.367 1.367 1.368 1.368 1.368 1.368 1.369 1.369 14 16 18 20 22 24 26 28 30 40 50 60 70 80 90 100 . . . . , CHAPTER XVIII. ARTESIAN WELLS. Definition. Strictly speaking, an artesian well should flow naturally over the top of the pipe without pumping. The name is very frequently but erro- neously applied to any bored well, but such wells merely differ from any ordinary well in the size of the hole and the method of lining it. Theory. Artesian wells depend for their success on the property of water finding its own level, or the tendency to stand at the same height in both the legs of a tube bent into the shape of a U. We must there- fore have for the source of water a region higher than the one where the well is to be sunk, and even then, owing to the friction in the ground and tube, the water will not rise quite to this level. Basin Wells. To secure the best results we must have a saucer-shaped basin of strata all dipping toward the center, and no part of the rim of the basin must be lower than the point at which the well is sunk (except as hereafter explained); and this basin must be filled with alternating layers or strata of material which will allow the ready flow of water, such as gravel; and others, such as clay, which will not per- mit its passage. Such a condition of the strata is shown in pi. 14, fig. 8. To make it more intelligible the vertical heights are made out of proportion to the horizontal, but this does not affect the principle. We have here three beds of clay, c,b,d, and two ARTKSIAN WELLS. 311 beds of gravel g and e, with surface dirt a. Now if a well be sunk at the center of the basin, as at w, it would penetrate all these beds. The upper bed of clay c would hold water, and if the well did not go through it we should have only an ordinary well. But as the stratum of clay c would prevent any water which fell on the surface exposure of the gravel g from reaching the surface again, this bed would form a reservoir in which the permanent water level would be the height of its lower outlet If then we extend the well into the gravel g we should make a lower opening and the pressure in the underground reservoir would force the water up the well, and perhaps over the top. But if we extend the well through g and the clay b into the gravel e we shall have tapped a larger reservoir, the gravel being thicker, with a larger sur- face exposure at a greater height, and the increased pressure will cause the water to rise above the top of the well, giving a permanent flow without pumping. This is a true artesian well. It might however happen, as in pi. 14, fig. 9, that a portion of the strata had been cut away and subse- quently overlaid by horizontal deposits as at c, but if these should be a retentive clay, the result would be the same, as the lower edges of the gravel g lying be- tween the beds of clay a t b y would be hermetically sealed by the clay c, and the well w would still be artesian on account of the pressure resulting from the altitude of a and b. From the foregoing it will be seen that the best results will be obtained in. those wells which are near- est the center of the basin. These will be under greater pressure than those nearer the rim of the basin, and the flow will gradually diminish as it is ap- proached, until those nearest to it, penetrating the retaining clay higher than the natural outlet, will have no overflow and become pumping wells. The central wells will, however, be more expensive to put down. 312 PROSPECTING AND VALUING MINES. Exceptional Cases. Otber causes, however, than the occurrence of saucer-shaped basins may give rise to favorable conditions for artesian wells, as in the case of San Bernardino in Southern California, which lies a few miles north of Colton. All the wells in the latter town are supplied with windmills, while in San Bernardino there are upward of 800 artesian wells, furnishing an immense flow of water. The quantity is so great that large irrigating ditches are supplied from this source. The boundary line between the two regions is a nearly straight line running west of north. Along this line there has been an immense fault across the wide valley of the San Gabriel River, with its alter- nating beds of clay and gravel, which has raised the solid rock on the west, until it acts as a retaining dam, converting the valley to the eastward into a huge underground reservoir, very much as in pi. 11, fig. 4, where AB may represent the fault, forming the reser- voir P, so that while wells to the left of A would re- quire windmills those at C might be artesian. (The illustration is drawn for a different purpose, but the relative position of the rocks and gravel beds is the same.) Here the water finds its way into the up- turned edges of the strata, bounded by the two walls of the valley, and not being able to pass the barrier of rock at the western end of the valley is forced to the surface through any opening piercing the retaining clays. That this is the case is proved by the wells being deep close up to the break or fault instead of encountering the retentive clays at gradually dimin- ishing depths going westward. Requisite Conditions. In the case just cited, the fault haviDg become impermeable, or not affording an out- let for the water, an artesian basin was formed where none would otherwise have been possible, but it does not always follow that because we have the proper shaped basin it will furnish an artesian flow. If the beds of clay are thin, very slight earthquake dis- ARTESIAN WELLS. 313 turbances may have broken them, so that they no longer act as retaining walls, but allow the escape of the water to other lower strata where it may be lost; or the gravel beds may not be continuous over large areas, but contained instead between two layers of clay united all round like the crust of a pie over the fruit, in which case there would be no pressure; and some- times, when the flow is small, a deeper sinking in search of a greater supply may allow the water to escape into a lower stratum having a natural outlet, and the flow be lost altogether. So many contin- gencies surround the successful sinking of artesian wells that only actual trial can determine the proba- bility of success, except in cases where obviously there can be no. extensive basin, as in broken moun- tain countries. The writer sunk 500 ft. in the San Joaquin Valley, Cal., but never found water which came nearer the top of the well than 12 ft., while further north, in what would have been deemed a less favorable locality, 18 out of 19 wells were successful and the deepest was less than 200 ft. While gravel has been spoken of as the source of water in the foregoing pages, it may be found in any other porous rock which will easily permit its flow, such as sand, sandstone, conglomerate, shale, chalk or even limestone, the essential point being that what- ever its nature it must lie between two non-permeable strata of clay or rock. The retaining strata, instead of clay, as assumed above, may be of any compact rocks such as hard and unbroken slates, quartzite, etc. Without these there can be no artesian well. When such a bed is found in sinking, the operator may expect satisfactory results, not otherwise; and if water is found beneath it in reasonable quantity care should be taken not to break the underlying one, for the reasons already given. If successful, artesian wells are invaluable for the 314 PROSPECTING AND VALUING MINES. water supply of cities and irrigation, as, though in some cases their first cost may be large, it is not inva- riably so, but on the contrary often quite moderate, and the annual repairs are nominal. Permanence of Supply. The well at Aire in Artois, France, has given a stream rising 11 ft. above the sur- face for the last 100 years, but in some cases where the success of the experiment has induced the sinking of a large number of wells in the same basin, the con- sequent increase in the size of the outlet, combined with excessive demands on the reservoir, has dimin- ished the pressure and reduced the flow, as in the London basin in England. Aside from such causes there is little to fear except from destructive earth- quakes which may rupture the strata, but fortunately these are rare. Examples. The following table of a few wells will give some idea of the depths which have been attained and show that there is no relationship between the depth of the well and the quantity of water obtained. In "Physical Data and Statistics of Calfornia," by W. H. Hall, there are minute details of many hundreds of wells varying in depth from 90 to over 1,000 ft., and with bores ranging from 2 in. to 7 in. As is the case elsewhere, many of the wells proved valueless for either drinking purposes or for irrigation on account of the large amount of mineral matter (chiefb 7 the salts of sea water) which the water contains, the amount running up to as much as 231 grains of solid matter per gallon; but the general results have been very satisfactory. The deepest bore reached a depth of 2,160 ft. without finding artesian water. ARTESIAN WELLS. SPECIMEN ARTESIAN WELLS AND BOREHOLES. 315 Locality. Depth. Ft. Diameter Inches. Flow in Gal. 24 Hours. Height. Ft. Temper- ature. Grenelle, France .'. Passy France 1798 1923 "*28" 864,000 5,582,000 54 82 82 Paris Basin France 300 to 400 2 8 London Basin 300 to 000 4 Chicago 700 to 1000 5 800000 Sperenberg Germany 4194 13 Louisville 2086 3 800 000 76^ Bourne England 95 500000 40 Philadelphia 200 g 50 000 California 72 4 271 000 2 67 California 85 3 139,000 2 68 California <. 90 4 239 000 3 California 95 7 465 000 68 California . . . . 100 3 224 000 2V California. . . . < 106 6 315,000 1 65Mj California 123 3 164000 2 California 123 7 1,011,000 ;" California 140 3 173 000 2 California 205 T 926 000 California 300 r~ 388000 7 64 USEFUL TABLES. ELEMENTS (CLARKE). Name. Sym- bol. Atom- icity. Atomic Weight. Sp. Gr. H=l. O=-16. Al Sb (?) As Ba Bi B Br Cd Cs Ca C Ce Cl Cr Co CborNb Cu Er F Gd Ga Ge BeorGl Au He H In I IV. V (?) V II V III I II I II IV III I VI IV V II (?) (?) (?) (?) II HI (?) I III I 26.91 119.52 (?) 74.44 136.39 206.54 10.86 79.34 111.10 131.89 39.76 11.91 138.30 35.18 51.74 58.55 93.02 63.12 165.06 18.91 155.57 69.38 71.93 9.01 195.74 (?) 1.000 112.99 125.89 27.11 120.43 (?) 75.01 137.43 208.11 10.95 79.95 111.95 132.89 40.07 12.00 139.35 35.45 52.14 58.99 93.73 63.60 166.32 19.06 156 76 2.502.81 1 6.626.86 ) 5.74 5.83 amorphous (?) ) 5.635.96 1 3.70 4.72 allotropic 3.75-4 9.67-10 2.532.68 2.95-3.19 7.99-8.69 1.87-1.89 1 55 1 80 AntimonyCstibni 1 m) Argon Arsenic Barium Bismuth Boron Cadmium Calcium f 3.33 3.55 diamond I 1.842.5 graphite 1 1.76-2.10 charcoal ^ 1.72-1.78 lampblack 6.63-6.73 1.33 liquefied 6.207.3 7.72-8.95 6-7.37 ( 8.398.96 < 8-8.2 allotropic ( 7.27-8.22 molten Cerium . . . . . Chlorine Chromium . < . . Cobalt Columbium (nio- bium). Copper (cuprum) . . Fluorine Gadolinium Gallium 69.91 72.48 9.08 197.23 (?) 1.008 113.85 126.85 5.93-5.96 5.469 1.64-2.01 19.219.47 (?) j .025-.033 liquefied Germanium Glucinum (berylli- Gold (aurum) Helium Indium ) .620 .628 occluded 7.117.42 j 4.82-5.02 solid 1 3.794 molten Iodine USEFUL TABLES. ELEMENTS (CLARKE). - Continued. 317 Name. Sym- bol. Atom- icity. Atomic Weight. Sp. Gr. H=l. O=16. Iridiuin Ir Fe La Pb Li Mg Mn Hg Mo Nd Ni N ds Pd Ph Pt K Pr Rh Rb Ru Sm Sc Se Si Ag Na Sr S Ta Te Tr Tl Th Tu Sn Ti W U V Yt Y Zn Zr IV VI in IV i ii VI II VI V VI II IV V IV I (?)] IV I VI (?) Ill VI IV I I II VI V VI (?) Ill IV (?) IV IV VI VI V III III II IV 191.66 55.60 137.59 205.36 6.97 24.10 54.57 198.49 95.26 139.70 58.24 13.93 189.55 15.88 105.56 30.79 193.41 38.82 142.50 102.23 84.78 100.91 149.13 43.78 78.42 28.18 107.11 22.38 86.95 31. as 181.45 126.52 158.80 202.61 230.87 169.40 118.15 47.79 183.43 237.77 50.99 171.88 88.35 64.91 89.72 193.12 56.02 138.64 206.92 7.03 24.28 54.99 200.00 95.99 140.80 58.69 14.04 190.99 16.00 106.36 31.02 194.89 39.11 143.60 10H.01 85.43 101.68 150.26 44.12 79.02 28.40 107.92 23.05 87.61 32.07 182.84 127.49 160.00 204.15 232.63 170 70 18 61 22 42 Iron (ferrum) f 7.48-7.87 bar 1 7.13 reduced by C \ 8.12 electrolytic | 6.88 molten i. 8.05 molten steel 6.05-6.16 ) 11.1611.50 } 10.3710.95 molten 5.78- 5.89 1.69- -2. 24 6.86 8.03 I 14. 15.19 solid 1 12.5713.61 liquid 8.498.64 Lanthanum Lead (plumbum) . . . Lithium Magnesium Manganese Mercury (hydrar- 1 gyruin) ..... f Molybdenum Neody mium Nickel 7,819.26 0.370.90 liquefied 21.422.477 0.581.24 liquefied 10.812.15 1.482.34 ( 19.5-21.8 -j 15.79-21. 15 spongy J20.98-22.89precip. .84 .87 [black Nitrogen . . Osmium Oxygen Palladium Phos phorus Platinum Potassium (kalium) Praseodymium Rhodium 1112.1 1.52 1112.26 Rubidium Ruthenium Scandium '"4.2-4.86"" 2-2.49 I 9.5510.62 J 9.12 10 molten 93 .98 2.40-2.58 1.46-2.09 10.0810.78 6.116.34 Silicon . Silver (argentum). . Sodium (natrium). . Strontium Sulphur Tantalum Tellurium Thallium. 11.78-11.91 10.9711.23; Thorium Thulium . Ti i (stannum) . . . 119.05 48.15 184.83 239.59 51.38 173.19 89.02 65.41 90.40 j 7.147.60 | 5.80 6.02 allotropic 16.619.26 18.2318.68 5.55.87 Titanium Tungsten (wolfram) Uranium , Vanadium Ytterbium . .- Yttrium Zinc 6.487.21 4.15 Zirconium 318 PROSPECTING AND VALUING MINES. The atomic weights here given have been compiled by Prof. F. W. Clarke from the most recent and reliable determinations and are adopted as stand- ard by the American Chemical Society. In addition to the foregoing there are a number of supposed elements-- actinium, holmium, idunium, ilmenium, mosaadrium, neptunium, phillippium and decipium, not accepted as valid by all chemists. Argon and helium, however, are placed in the list, though little is known about them. The wide range in specific gravity is due to impurity of samples in some cases; temperature when tested; with metals whether cast, rolled, ham- mered, etc. ; and to the fact that the determinations were made by different chemists using different methods. In the older chemical nomenclature oxygen v as assumed as 16 to 1 of hydrogen. Later determinations give 15.88 to 1. Consequently the values of atomic weights are calculated on two scales, on one of which hydrogen is taken as 1, and on the other, oxygen as 16. The differences are only fractional. GENERAL CLASSIFICATION OF MINERALS (BRUSH). I. MINERALS WITH METALLIC OR SUB-METALLIC LUSTER. NOTE. Minerals having metallic luster are opaque, and do not transmit light even through their thinnest edges. The color of their powder, or their streak, is therefore dark, though not necessarily black. The minerals with sub-metallic luster which are included in this section all give dark-colored streaks. Many dark-colored minerals whose luster is doultful have been placed here, and also in Section II. A. FUSIBLE PROM 1 TO 5 OR EASILY VOLATILE. 1. Arsenic Compounds. B. B. on charcoal give a volatile coating of arsenious oxide. 2. Selenium Compounds. B. B on charcoal give a characteristic radish-like odor and impart an azure-blue color to the reducing flame. 3. Tellurium Compounds. When treated in a test-tube with 5 cc. of concen trated H 2 SO 4 and gently heated, the acid assumes a reddish-violet color. 4. Antimony Compounds. B. B. on charcoal give a dense white coating of oxide of antimony. 5. Sulphides. When roasted in the open tube or on charcoal give the odor of sulphurous anhydride, but do not give the reactions of the preceding divisions. 6. Not belonging to the foregoing divisions. B. INFUSIBLE, OR FUSIBLE ABOVE 5, AND NON-VOLATILE. 1. Iron Compounds. Become magnetic after heating B. B. in the reducing flame. 2. Manganese Compounds. Impart to the borax bead in O, F. a reddish- violet color. 3. Not belonging to the foregoing divisions. II. MINERALS WITHOUT METALLIC LUSTER. NOTE. Minerals without metallic luster are transparent, although they may have such an intense color that they transmit light only through very thin edges. The color of their powder, or their streak is generally white or light-colored, never black. A. EASILY VOLATILE, OR COMBUSTIBLE. Eapidly disappear when heated B. B. on charcoal. USEFUL TABLES. 319 B. FUSIBLE FROM 1 TO 5, AND NON-VOLATILE, OR ONLY SLOWLY OR PARTIALLY VOLATILE. PART I. Give a Metallic Globule when fused with sodium carbonate on charco 1. J. Silver Compounds. B. B. with sodium carbonate on charcoal give a globule of silver. 2 Lead Compounds. B. B. with sodium carbonate on charcoal give a globule of lead. 3. Bismuth Compounds. B. B. with sodium carbonate on charcoal give a globule of bismuth. 4. Antimony Compounds. B. B. with sodium carbonate on charcoal give a globule of antimony. 5. Copper Compounds. B. B. with sodium carbonate on charcoal give a globule of copper. The powdered mineral on charcoal, after moistening with hydrochloric acid, imparts an azure-blue color to the blowpipe flame. PART II. Iron Compounds. Become magnetic after heating before the blowpipe in the reducing flame. 1. Sulphates, Arsenides, and Phosphates, chiefly. Soluble in hydrochloric or nitric acid without a perceptible residue, and without yielding gelatinous silica upon evaporation. 2. Silicates. Soluble in hydrochloric or nitric acid, and yield gelatinous silica upon evaporation, or decomposed with the separation of silica. 3. Not belonging to the foregoing divisions. Insoluble in hydrochloric acid. PART III. When fused with sodium carbonate on charcoal do not give a metallic globule, and when fused alone in the reducing flame do not become magnetic. 1. Salts of the Alkali and Alkali-Earth Metals. After intense ignition be- fore the blowpipe, either in the forceps or on charcoal, the ignited material giv s an alkaline reaction when placed on moistened turmeric paper. a) Easily and completely soluble in water. b) L soluble in water, or difficultly or only partially soluble. 2. Arsenates. Phosphates and Borates, chiefly. Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica upon evaporation. 3. Silcates. Soluble in hydrochloric acid, and yield gelatinous silica upon evaporation. a) In the closed tube give water. b) In the closed tube give little or no water. 4. Silcates. Decomposed by hydrochloric acid with the separation of silica, but without the formation of a jelly. a) In the closed tube give water. b) In the closed tube give little or no water. 5. Not belonging to the foregoing divisions. Insoluble in hydrochloric acid. C. INFUSIBLE, OR FUSIBLE ABOVE 5. 1. Salts of the Alkali-Earth Metals. After intense ignition before the blow- pipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed on moistened turmeric paper. 2. Carbonates. Sulphates, Oxides, Hydroxides and Phosphates, chiefly. Soluble in hydrochloric acid, but do not yield a jelly or residue of silica upon evaporation. 3. Silicates. Soluble in hydrochloric acid, and yield gelatinous silica upon evaporation. 4. Silicates. Decomposed by hydrochloric acid with the separation of silica, but without the formation of a jelly., 320 PROSPECTING AND VALUING MINES. 5. Not belonging to the foregoing divisions. Insoluble in hydrochloric acid. a) Hardness less than that of glass or a good quality of steel. Can be scratched by a knife. b) Hardness equal to or greater than that of glass. Cannot be scratched by a knife. CHARACTERS OF MINERALS (DANA). 1. Name, synonyms. 2. Crystalline, form and structure. System of crystallization. Axial ratio and angular elements. Twinning General structure, amorphous varieties, initiative forms, etc. 3. Physical characters : Cohesion, Cleavage, Fracture, Hardness. 4. Characters relating to Heat, Electricity, Magnetism. 5. Taste and odor. 6. Chemical composition. 7. Pyrognostic qualities (blowpipe). SYSTEMS OF CRYSTALLIZATION (DANA). I. Isometric 3 equal axes, at right angles to each other. (Ex. cube, octa- hedron , dodecahed ron = py rite). II. Tetragonal 3 axes. The 2 lateral axes equal, the vertical axis longer or shorter: all at right angles to each other. III. Hexagonal and Rhombohedral, 4 axes; 3 lateral axes in same plane at 60 from each other and a fourth vertical axis at right angles to them and either longer or shorter. In the Hexagonal system proper there are 4 principal planes of symmetry; 3 equal planes intersecting at 60, and a fourth unequal, normal to them ; also 3 auxiliary planes diagonal to the first set (ex- ample, apatiie group). The Rhpmboheclral system includes forms with only 3 planes of symmetry intersecting at 12u in the vertical axis. (Ex. rhombohe- dron many forms of calcite and tourmaline). IV. Orthorhombic 3 unequal axes at right angles to each othe-; 3 planes of symmetry, which intersect in these axes but are all different. V. Monoclinic 3 unequal axes, of which one lateral axis is inclined to the vertical axis, the other angles right angles; 1 plane of symmetry. VI. Triclinic 3 unequal axes, and their intersections are all oblique. MINERAL CHARACTERS DEPENDING UPON 'LIGHT (DANA). Kinds of Luster : 1. Metallic; sub-metallic. 2. Adamantine (like diamond). 3. Vitreous (like broken glass). 4. Resinous (like yellow resinj. 5. Greasy (like elaeolite). 6. Pearly. 7. Silky (the result of a fibrous structure). USEFUL TABLES. 321 Degrees of Intensity : 1. Splendent. 2. Shining. 3. Glistening. 4. Glimmering. INDIVIDUALIZATION OF CRYSTALS (CROSBY). I. Distinct, separate and so nearly perfect minerals that their proper forms may be clearly recognized^ crystallized. II. Confused mass showing crystal faces or planes and cleavage planes. but no perfect crystals (rock salt and white marble) crystalline or massive. III. Crystalline form and cleavage both entirely wanting to the unaided eye, but the specimen shows double refraction when a thin section is viewed by polarized light (chalcedony)=cryptocrystalline or com- pact. IV. Entirely devoid of crystallization (opal and obsidian) amorphous. Implanted crystals =crystals of uniform size thickly set on a surface. Drusy=very small implanted crystals. INTERNAL STRUCTURE OF MINERALS (CROSBY). Granular Fine to coarse = in grains. Compact or impalpable=when the grains are invisible to the naked eye. Glassy or vitreous=no trace of granular structure even under microscope; may be crystalline (like vitreous quartz) or amorphous (like obsidian). Lammellar= lamination independent of crystallization, or dependent. In the first case called b ;nded; in the second, foliated. Fibrous=if coarse, called columnar or baaded. EXTERNAL FORMS OF MINERALS (CROSBY). Botryoidal=rounded, grapelike. Mammillary= larger rounded prominences. Stalactitic= deposited from solution by dripping water from overhanging rock. Stalagmitic^Deposited from solution by dripping water on floor of caves, etc. Tufaceous porous deposits formed when reeds, grasses, moss, etc., are in- crusted by mineral solutions. Concretionary = rounded mass or nodule produced by aggregations of min- eral matter in the body of a rock. Pisolitic if the concretions are small (about size of peas). Oolitic = if very small (fish roe or mustard seed). Geodes=hollow concretions. Amydaloids almond shaped, deposited in the vesicles or steamholes of lava Dendritic, arborescent, mossy = (stains of iron and manganese, native copper, etc.), resembling vegetation. Reticulated. = net-like. Plumose feather-like. Filiform wire or thread-like. Acicular=like needles. FRACTURE (CROSBY). Conchoidal = shelly. Even. Uneven. Earthy (like clay or chalk). Hackly. Splintery. 322 PROSPECTING AND VALUING MINES. SCALE OF FUSIBILITY OF MINERALS (VON KOBELL). 1. Stibnite (antimony glance), large fragments are fusible in the ordinary flame of a candle. 2. Natrolite; fine needles are fusible in the flame of a candle; large frag- ments fuse to a globule B.B. 3. Almandite (alumina-iron garnet); infusible in the flame of a candle; can be fused to a globule B.B. if in small fragments. 4. Actinolite (var. amphibolite): fusible to a globule in fine splinters B.B. 5. Orthoclase: in very fine splinters is still fusible to an irregular globule; if in larger fragments only the edges are rounded B. B. 6. Bronzite (diallage); only the finest edges or points can be rounded B.B. To these Crosby adds : 7. Quartz; infusible alone, B.B. THE GEOLOGIC SERIES, ACCORDING TO LE CONTE. Eras. Ages. Periods. Epochs. 5. Psychozoic . . 7. Age of Man. Human. 23. Recent. 4. Cenozoic... 6 . Age of Mamm als . . f Quaternary 22 ( Terrace. < Cham plain. ( Glacial. ( Pliocene. < Miocene. ( Eocene. j [.Tertiary 21 3. Mesozoic . . . 5. Age of Reptiles ( Cretaceous ... 20 -< Jurassic 19 ( Triassic 18 Upper. 2. Palaeozoic... Lower. CARBONIFEROUS 4. Age of Acrogens and Amphibians. ( Permian 17 -\ Carboniferous 16 ( Sub-carboniferous. 15 DEVONIAN. 3. Age of Fishes ( Chemung . . . 14 J Hamilton 13 1 Corniferous 12 LOriskany 11 SILURIAN. 2. Age of Invertebrates CAMBRIAN. f Helderberg . . .10 Salina 9 Niagara . 8 Trenton 7 [ Canadian 6 ( DikelocephaPs zone 5 < Paradoxides zone. . 4 f Olenellus zone 3 1 . Archaean or Archaezoic 1 Archaean \ Huronian 2 / Laurentian 1 USEFUL TABLES* 323 THE GEOLOGIC SERIES, ACCORDING TO DANA. [See also p. 68 for the system adopted by the U. S. Geological Survey.] Age of Man, or Quaternary. Mammalian Age. Tertiary Period. Reptilian Age. Cretaceous. Jurassic. Wealden (epoch). Oolitic (epoch). Liassic (epoch). Triassic. Carboniferous Age. Permian. Carboniferous. Sub-carboniferous. Devonian Age, or Age of Fishes. Catskill. Chemung. Hamilton. Corniferous. Silurian Age, or Age of Inverte- brates. Upper Siluria-i. Oriskany. Lower Helderberg. Salina. Niagara. Lower Silurian. Trenton. Canadian. Primordial, or Cambrian. Below the Lower Silurian come the azoic schists and granite. 324 PROSPECTING AND VALUING MINES. CLASSIFICATION OF ROCKS. A. Igneous Rocks. B. Aqueous and IGNEOUS Glassy. Acid Glasses. Obsidian, Perlite, Pumice, Pitchstone. Chief Feldspar Orthoclsae. Chief Feldspar Biotite (or) (and) Hornblende (or) (and) Auglite. Biotite (or) (and) Hornblende. +Quartz. Quartz. Nepheline or Leucite. +Quartz. Quartz. TRACHYTE GROUP. ANDESITE GROUP. Felsitic and Rhyolite. Trachyte. Phonolite (rare). Dacite. Andesite. Porphyritic. (Quartz Porphyry.) (Prophyry.) Leucite Phonolite (very rare). (Porphy- rite.) (Porphy- rite.) (Quartz Felsite.) (Felsite.) Fragmental. Rhyolite Tuff and Breccia. Trachyte Tuff and Breccia. Phonolite Tuff and Breccia. Andesitic Tuff and Breccia. GRANITE GROUP. DIORITE GROUP. Granitoid. Granite (Pegmatite) Syenite (rare). Nepheline- Syenite (rare). Leucite- Syenite (very rare). guartz- iorite (Tonalite). Diorite. Si0 3 . 80.65# 65.55# 60.50# 70.60# 65.05$ USEFUL TABLES. 325 ACCORDING TO PROF, J. F. KEMP. ^Eolian Rocks. C. Metamorphic Rocks. ROCKS). Andesite Obsidian. Basic Glasses, Scorias, Tachylite, Basic Obsidian. Plagioclase. Nepheline, Leucite. No Feldspar. Pyroxenes. A Series of Rare Basaltic Rocks. Augite (or) (and) Hornblende (or) (and) Biotite. ~ Olivine. +Olivine. Olivine. -fOlivine. Augite- Andesite. Oli vine- free Basalt. (Diabase.) Basalt. Dolerite. (Oli vine- Diabase.) With Nephel- ine, Leucite ( eldom Meilite) one or all. Not readily distinguishable from Basalt without the microscope. Extremely rare in America. Augitite. Limburgite Not readily distinguish able from Bas lit. Extremely rare in America. Basaltic Tuffs and Breccias. GABBRO GROUP. Diabase. Gabbro. Anortho- site. Olivine- Diabase. Olivine- Gabbro. Theralite (extremely rare). Pyroxen- ite. Peridotite. Ice. Norite. Olivine- Norite. 55.45$ 45.38# 55.40:* 45.300J< 30.00# Ultra-basic Rocks. Basic Segrega- tions in normal Magmas. Meteorites. Water. 326 PROSPECTING AND VALUING MINES. THE PRINCIPAL Grand Divisions. Origin. Structure. Material. Incoherent State. Sand. Gravel. Shingle. I Rubble, f Arenaceous or sandy. Volcanic frag- ments. Volcanic ash. Stratified. Aqueous and .^Eolian (the latter only slightly stratified, of fine mated Is usually not compacted). More or less earthy. Argillaceous or clayey. Mud. Clay. Calcareous or limey. Ooze. Chalk. Chemical pre- cipitate. Metamorphic or Transition. Aq'.eous, with subse- quent heat, pressure and chemical agencies. Roughly stratified; in part crystal- line; usually fissile. USEFUL TABLES. ROCKS (LE CONTE). Compacted State. Essential Components. Remarks. Sandstoi.e. Silica, often with iron oxide. Grit. Small pebbles (mostly quartz) ce- mented with silica and iron oxide. Conglomerate. Large pebbles and bowlders similarly cemented. Breccia. Angular fragments (usually volcanic) of various rocks, cemented with silica and iron oxide. Tufa. Fine volcanic dust compacted under water. Shale, Indurated particles of clay, usually with some quartz grains and iron oxide. Limestone. Calcite, amorphous or partly crys- talline. Magnesian lime- i y stone, dolomite, f Dolomite and calcite. Magnesite. Magnesite. Gneiss. Mica, quartz, feldspar. Mica schist. Mica, quartz, feldspar. Chlorite schist. Chlorite, quartz, feldspar. Talcose schist. Talc, quartz, feldspar. Hornblende schist. Hornblende, quartz, feldspar. Garnet schist. Garnet, quartz, feldspar. Slate. Hardened shale, cleavage across stratification planes. Quartzite. Altered sandstone. Marble. Altered limestone, calcite. Serpentine. Altered magnesian minerals. 328 PROSPECTING AND VALUING MINES. THE PRINCIPAL Grand Divisions. Origin. Structure. Material. Occurrence. Occurring massive. Unstratifled. Igneous. Crystalline. Plutonic or massive. Occurring in intrusions. Volcanic or true eruptives. Occurring in overflows. Besides the essential components there are many minor u accidental " rphic such as magnetite, pyrite, olivine, etc., but these usually occur in USEFUL TABLES. ROCKS (LE CONTE). (Continued.) 329 Compacted State. Essential Components. Remarks. ACIDIC Pegmatite (graphic Large plates of mica imbedded in granite). feldspar. Granite. Quartz, orthoclase feldspar, mica. Eurite or granulite. Syenite. Quartz syenite. A fine-grained granite. Orthoclase feldspar, hornblende. Quartz, orthoclase feldspar, horn- Entirely crystalline (holocrystalline) ; blende. usually coarse Porphyritic granite Large crystals of feldspar in a finer groundmass. grained (microcrystalline). BASIC-r Diorite. Plagioclase feldspar, hornblende. Quartz diorite. Plagioclase feldspar, hornblende, quartz. Gabbro. Plagioclase feldspar, augite, < livine (granitoid variety of diabase). ACIDIC Quartz porphyry. Microcrystalline groundmass, with Felsite. larger crysta's of orthoclase and quartz. Microcrystals of orthoclase and Microcrystalline groundmass, with or without BASIC Diorite. quartz. Piagioclase and hornblende (micro- larger crystals imueaaeci. crystalline). Diabase. Augite and hornblende (microcrys- talline). ACIDIC Glassy ground- Rhyalite. Vitreous groundmass. with crystals mass, with fine to of quartz an orthoclase coarse crystals im- (sanidin). bedded, or wholly Trachyte. Vitreous groundmass, with crystals vitreous. Usually of orthoclase (sanidin). fine-grained (micro- Phonolite. Light colored Vitreous groundmass, with crystals of sanidin and nepheline. crystalline) or im- oerfectly crystal- scoriae. Pumice. ine (cryptocrystal- ine). The following Obsidian. exist in the stony BASIC condition ; rhyolite, Andesite. Vitreous groundmass, with crystals iparite, trachyte, of plagioclase, augite or hornblende. Dhonolite, basalt, dolerite and ande- Basalt. Vitreous groundmass, with crystals of plagioclase, augite and olivine. site. The following are glassy: Scoriae, Black scoriae. Tachylite. pumice, obsidian, and tachylite. or accessory minerals in most rocks, especially in the igneous and meta- small proportions. 330 PROSPECTING AND VALUING MINES. CLEAVAGE (CROSBY) Kinds : In the isometric (I.) system I Cubic, octahedral dodeca- tetragonal (II.) system f hedral, etc. hexagonal and rhombrohedral (III.) system! orthorhombic (IV.) system. ) \ prismatic, basal and monoclinic (V.) system ..... > pinacoidal . . . . / pyramidaL triclinic (VI.) system . . . . ... ) J Degrees : Perfect or eminent (like mica). Distinct. Indistinct or imperfect In traces. Difficult. MINERALS DISTINGUISHED ACCORDING TO TOUCH OR FEEL (CROSBY). Meager (like chalk, clay, etc). Smooth. Harsh. Unctuous. Rough. Greasy. MINERALS DISTINGUISHED ACCORDING TO TASTE (CROSBY), Astringent. Saline. Cooling. Alkaline. Sour. Adhesive. Bitter. MINERALS DISTINGUISHED ACCORDING TO ODOR (CROSBY). Sulphurous. Argillaceous (like clay) Arsenical (like garlic). Fetid (like some limestones). Horseradish (selenium). SCALE OF HARDNESS (MOHS). 1. Talc (foliated), very soft. 2. Gypsum (compact alabaster), can be scratched by the finger nail. 3. Calcite, can be crushed between the teeth. 4. Fluorite, easily scratched by knife steel. 5. Apatite, about the hardness of knife steel. 6. Feldspar (orthoclase), easily scratched by quartz. 7. Quartz (crystalline), scratches ordinary glass. 8. Topaz, easily scratches quartz, 9. Corundum, scratched only by diamond. 10. Diamond, the hardest mineral known. Dr. F. M. Endlich says : " In testing the hardness of a mineral by this scale, care should be taken that the pure mineral, not a mixture, is obtained. If a mineral scratches calcit , but is scratched by fluorite, to about the same degree, its hardness lies nearly midway between 3 and 4, and is expressed by 3.5. If it barely scratches calcite, but is decidedly scratched by fluorite, the hardness is 33.5; if nearer to fluorite in hardness, but still scratched by it, the hardness is 8.5-4." USEFUL TABLES. VALUES OF METAI^, ORES, MINERALS, ETC. 331 [Quotations are those ruling in the United States January 1, 1899. The selling point, when not otherwise stated, is assumed to be New York City.] Substance. Unit. Price. Remarks. NON-METALLIC. Abrasives: Corundum . . . <, Lb. Long ton. Long ton. Short ton. Short ton. Lb. Short ton. Lb. Lb. Short ton. 100 Ib. 100 Ib. Short ton. Short ton. Short ton. Short ton. Long ton. Lb. Short ton. Lb. Lb. Bbl. Bbl. Bbl. Short ton, Long ton. Short ton. Short ton. Long ton. Short ton. Short ton. Short ton. Short ton. Short ton. Lb. 100 Ibs. Lb. Lb. Short ton. Short ton. Short ton. IOC Ib. 4.5-lOc. $20. 00-40. 00 18.50-32.00 38.00-57.00 10.50 4-40c. $3.00 6-18c. 17-30c. $12.00 1.65 1.25-1.75 19.50 f 40.00 ! 18.00 j 30.00 I 40.00-60.00 12.12 j 7.75 1 10.00 3.00-4.50 3^-5c. $&E 6% 7^C. Best ground Crude Naxos. Lump. Lump. Lump. Lump. Best Cuban. Lower grade. Trinidad. Utah gilsonite. Crude. Best. Crystal and Powder Barrels of 300 Ibs. Barrels of 400 Ibs. Barrels of 350 Ibs. Commercial lump. J Domestic f. o. b at 1 works. Best Scranton, Pa. Pittsburg. Denver. Pittsburg. Denver. Best grade. From Greenland. Ground. Lump. Crushed. Lump. Diatomaceous or in- fusorial earth ..... Emery Rottenstono Tripoli Aluminum sulphate.. . . Asbestos Asphaltic limestone. . . . Barytes Bauxite Bituminous sandstone . Borax Bromine 45c. 65c.75 $1.75@,2.50 1.65 2.00-2.10 $20.25 7.50-9.50 4.00-5.00 2.00 40-70c. $2.95 1.25 1.84 1.25 $1.76-1.85 57^c.65c 3%c. 4c 8^c. $7.00-7.75. 2.50-4.00 6.00 75c.85c Cement, natural hy- draulic .... Cement, Portland Cement slag . . . Chalk Chrome ore day china Clay fire Coal, anthracite, stove Coal bituminous Coal cannel Coal lignite Coke, Connellsville .... Coke, Trinidad Cobalt, oxide Copperas Copper sulphate Cryolite . .... Feldspar Flint silica Fluorspar Fuller's earth 332 PROSPECTING AND VALUING MINES. VALUES OF METALS, ORES, MINERALS, 'ETC.- Continued. Substance. Unit. Price. Remarks. Grahamite Short ton. Lb. Long ton. 100 Ib. Long ton. Long ton. Long ton. Bbl. Short ton. Short ton. Long ton. Short ton. Lb. $33.00 lM-4^c. $4.00 2.55 3.25-3.65 2.10-3.25 j J 3.25-3.65 i 2.55-3.25 75c.-$1.00 $91.50 7.00-8.00 2.05 8.00 4-6c. 1 Ceylon, crude. Rock. Crude. Cleveland, bessemer. Cleveland, non-bes- semer. Cleveland bessemer. " Non-bessemer. Barrels of 250 Ibs. Crude lump. 501 According to size and quality. Slag. H 92#. Imported. American. American. American lead. Chinese quicksilver. English quicksilver. American, dry. American, extra dry. Bbl. of 42 gal., crude. American lump ore, Barrels of 280 Ibs. Crude. " Square " = 100 sq. ft. as laid on roof. Lump, Sicilian. Southern. New York. 98& 9o#; Sheets. Nickel alloy. Cookson's. Other. Lake. Pittsburg. At furnace. Graphite (plumbago).. Gypsum . . . iron ore, hematite Iron ore limonite. . Iron ore, magnetite. . . . Litharge Manganese ore . . Marble flour , . . . Mica ground .... 100 Ib. Short ton. Lb. Short ton. Lb. Lb. Lb. Lb. Bbl. P. unit. Gal. Long ton. Bbl. Lb. Short ton. Square. Short ton. 100 Ib. Lb. Long ton. Short ton. Short ton. Lb. Lb. Lb. Lb. Long ton. Troy oz. Long ton. $1.00-4.00 140.00 6-8c. $8.00-15.00 5M-6c. ( 14-1 6c. 4 90c. ( 90c. 4V4-6C. ^- 7-10c. Be. $3.25-5.00 3.50-6.00 3-3%c. $4.00-6.00 2. 25-10. 50 -j 11.00 1.50-1.60 13-1 4c. $19.00-21.50 10 00 15 50 Monazite Paints ocher Paints red led Paints vermilion Paints white lead .... Paints zinc white .... Phosphate rock Pitch coal tar Pyrites Salt ground Saltpeter Slate ground Soapstone Sodium nitrate Strontium carb. prec . Sulphur Talc common Talc, fibrous 8.00-9.00 2.00-3.00 ( 30-34c. 30-43C. 1 38c. [ 33-39c. J 9i4c. 1 8-M-8%c. 12%c. $50.00 20.67 11.25 11.50 Uranium oxide METALS. Copper Ferromanganese Sold Iron, No 2 foundry. . . . USEFUL TABLES. 333 VALUES OF METALS, ORES, MINERALS, ETC. Continued. Substance. Unit. Price. Remarks. Iridium Gram $1.19 Price in Germany Lead. ... 100 Ibs 3 75 New York Nickel Lb 33 36c Accord'sr to Quantity Platinum. . Troy oz $14 50 16 00 Quicksilver Flask 41 00 New York; flask of Silver.... Troy oz 59^3 60c 76^ Ibs. Com''! valu Spiegeleisen Long ton $23 00 Zinc 100 Ib 5 00 New York RARE ELEMENTS. [Prices given are ai makers' works in Ger many, unless other wise noted.] Barium Amalgam Electrol Gram. Gram. $1.19 5.71 Beryllium Powder Crystals '. . . Gram. Gram. 5.95 9.04 Nitrate Oz 2 50 New York Boron- Amorphous, pure Crystals, pure Nitrate Gram. Gram. Lb 19c. : $1.43 1 50 New York Calcium Elect' ol Cerium Fused Lb. Gram 4.28 2 02 Nitrate Lb 28 00 New York Chromium Fused Pure powder Kg. Kg. 5.95 1 79 Chem. pure cryst Cobalt (98@99$) Gram. Ke- 19c. $5 35 5 71 Pure if: 30 94 Didymium Powder. . . Nitrate Gram. Oz 3.81 4 00 New York Erbium Gram 3 09 Nitrate Oz. 3.00 New York Gallium. Grain 9 52 Germanium Powder. . Fused Gram, Gram 33.32 35 70 Glucinum Powder Crystals ... Gram. Gram 5.95 9 04 Nitrate , Lb. 2.50 New York Indium . . . Gram. 4 05 Lanthanum Powder... Electrol, in balls Gram. Gram. Oz 4.28 9.04 3.50 New York Lithium Gram 2 38 Nitrate Molybdenum Po *vder Fused, electrol Niobium Oz, Kg. 100 grams. Gram 60c. $2.62 15.47 3 81 New York. Osmium Gram 95c Palladium Sponge Sheet and wire Gram. Gram. . 95c. $1.70 334 PROSPECTING AND VALUING MINES. VALUES OF METALS, ORES, MINERALS, ETC. Continued. Substance. Unit. Price. Remarks. Rhodium Gram $2 87 Rubidium Pure Ruthenium Pure Selenium Com! pwd'r Sublimed powder. . . . Sticks Gram. Gram. Kg. Kg. Kg 4.76 1.55 26.18 35.70 28 56 Silicium Amorphous.. Crystals pure 100 grams. 100 grams 2.87 7.14 Strontium Electrol.. . . Tantalum Pure Gram. Gram 6.19 3 57 Tellurium C. p. sticks Powder 100 grams. 100 grams. 11.90 9.52 Thallium 23 80 Thorium- Nitrate, 45@-50$ Gram. Lb. 7.85 7.50-8.00 New York, Titanium Gram. 71c. Uranium Gram. 48c. Nitrate Oz 25c. New York, Vanadium Fused ..... Wolfram Fused Gram. 100 grams $1.19 23.80 Powder, 95@98 Chem pure . . If: 2.38 7.14 Ore IS 47.60 Lump. Yttrium . Gram 3.33 Nitrate Oz. 4.00 New York. Zirconium Com 1 ! . . Ks 119 00 Pure Gram. 71c. Nitrate Oz $1.00 New York. USEFUL TABLES. 335 H g ^ H <1 I 2 H 02 ^ H ^ fe g O $3 O o fo O if2 O O T i eo TH fc- W C- O -^ J> TH Tf 00 TH O O TH TH TH C^ <>* C? CO SPA - q ooooooooo SJ918UI -T1U80 ;C!ir!GCTtOCC i OTHC3coTt-oo ^ saonnQ otquo -0112 o TH od co "* to CD J> 06 Ol ia O O O TH TH T sjaiara | g^ -HUM i ^ ^ seqoaj K5J If PI! bJOttfi ..jo S OJ 1O TH ^ II II II II o; spanod siodnpjiOAy O O TH TH (M (TJ CO CO r o; saonnQ ! c I! II II H II II II II II TH OS ?i 1C pmi^ 01 SJ91HPU90 ooTHTHT- I D \ B /I Fig 6. Fig 7. PLATE 10. Figs. 1, 2, 3. Formation of the ancient buried gold-bearing river deposits in California. Fig. 4. Probable length of tunnel to tap the "channel." Fig. 5. Side ravine or so-called "overflow" of gold-bearing gravel. Fig. 6. Basalt cone (6), through gravel bed (d) 3 at Laporte, Cal 362 Fig.!, Plate JO ' Fig: 2. Fig. 3. Fig. 4. Fig.5, Fig. 6. PLATE 11. Fig. 1. Showing present shape and condition of the ancient California river channels; horizontal plan. Fig. 2. Cross section of Breece & Wheeler placer mine, California. Fig. 3. Petrified tree, coated with iron pyrite, Sailor Flat, Cal. Fig. 4. Fault in placer beds, Grass Flat, Cal. Fig. 5. Eeverse throw of placer beds, Laporte, Cal. Fig. 6. Faults in gravel bed, caused by dikes. 364 Fig. 2 Fig.3- Fig. 4 Fig.5 Fig. 6 C PLATE 12. Figs. 1, 2. Folding of gravel beds at Tacoma, Wash. Fig. 3. Section of river bed, showing effect of the bed rock on the retention of gold. Fig. 4. Slate quarry, showing stratification lines, B y B, and cleavage lines, L, L. Fig. 5. Contact vein, Garibaldi mine, Cal. Fig. 6. Unconformable gravel beds, divided by a bed of sinter. Fig. 7. Changes of currents of water in a gravel deposit, with petrified trees, Sailor Flat mine, Cal. Fig. 8. Folding of slates by pressure of dike (D). Fig. 9. Canon or ravine, following fault, Death Valley, Cal. 866 Fig.2 Fig. 3. Bed of Fig, 6 Fig, 7 Fig. 9 PLATE 13. Figs. 1, 2, 3, 4, 5, 6, 7. Data for estimating quan- tity of ore in a mine. Fig. 8. Miner's born spoon. Fig. 9. Development of mines. Figs. 10, 11, 12, 13. Strike and dip of outcrop. Fig. 14. Mica crystal, Fig. 15. Hornblende crystal. Fig. 16 Augite crystal. 368 PLATE 14. Figs, 1, 2, 3, 4, 5, 6, 7. Showing method of mak- ing locations, good and bad. Fig. 8. Artesian well in basin with continuous rim higher than pipe outlet; c, b, d, clay beds; g and e, gravel beds; a, surface dirt; w, well. Fig. 9. Artesian well in basin with rim defective on one side; but which flows because the basin is sealed by the water-tight clay bed c; g, gravel bed; a and b } clay seams; w, well. 370 Fig.5 PLATE 15. Figs. 1, 2. Correct form of blaze on trees as witness marks. Fig. 1, front view; fig. 2, side view. Figs. 3, 4. Good (3) and bad (4) stone-and-stake monuments. Fig. 5. Posting location notice in tin can. Figs. 6-12. Making locations (see Chap. X.), Figs. 13, 14. Blind lodes; longitudinal and cross sections. 378 Fig.5. Fig. I. Fig 2 Fig 5. ff.q.S. Del?. INDEX. Abyssinia, Erosion in 159 Adamantine 207 Agricultural rights 172 Alabaster 48 Alston Moor mine 101 Altenberg mines 116 Amador mines 102 Amorphous. . . . . . . . 207 Anglesite 216 Annabergite 224 Anthracite 262 Anticlines 146 Antimonial silver 210 Antimonides and arsenides 132 Antimony and country rocks.... 128 Antimony ores 226 Apatite 39 Aqueous theory 106 Arastra 28 Arborescent 207 Area vein worked 33 Argentite 210 Arsenic 226 Arsenical pyrite 221 Arsenides and antimonides 132 Artesian wells 310, 315 Asbestos 229 Asbestos in hornblende rocks 164 Asphaltum 231 Assaying 24 Assessment work 171 Atacamite 215 Atomic weight 316 Attle 205 Augite 39 Autunite 228 Azurite 214 B Backs 34 Bald Mountain 134 Bars, River 298 Barytes 229, 231 Basalt 51, 54, 58 Basalt, Prospecting in 164 Batopilas .6, 101, 103 Bauxite 232 Becker, G. F., on Steamboat Springs 107 Bedding planes 41 Bedrock 275, 287 Beds, Dip of 146 Beds, Ore ................. 144 Beds, Outcrops of 147 Beds, Thickness of 69 Beds, Workable 71 Bendigo mines 133 Bibliography 338 Bismuth, Native 226 Bismuth ores 226 Bituminous coal 263 Black silver , 211 Blende 218 Blende and galena. Separating.... 26 Blind lodes....... 77 Bog iron ore 8, 143 Books of reference 338 Borate of lime 251 Borax 142, 251 Borehole records 315 Borehole, Sperenberg 141 Borings for coa^ 10 Borings in gravel 10 Borings, Useless 8 Bornite 213 Botryoidal 207 Bottom gravel 275 Bowlder clay 67 Breccia 66 Breece & Wheeler mine 277 Brick clays 243 Brilliant 207 Brittle 207 Brittle silver 211 Bromide of silver 116, 211 Buhrstones 61 Bulk of ores 18 Burchardite 213 C. &C. shaft 109 Cadmium 227 Calamine 217 Calaverite . . 210 Calico district. . . . , 105 Cannel coal 265 Canon Creek 158 Cap rock 278 Carbonate of copper 214 Carbonate of lead 216 Carbonate of zinc 217 Carmen island salt. 141 Carpenter F, B., on Dakota gold mines 134 Cascade range 136 INDEX. 375 Caspian sea salt . . . , 141 Caves 148 Caving 13 Celestite , 247 Cerargyrite 211 Cerussite 216 Chalcocite 213, 215 Chalcopvrite 212 Chalk..: 45 Charges for locations 191 Cheshire salt 141 Chile saltpeter 255 Chloride of copper 215 Chloride of silver 116, 211 Chlorite 89 Chlorite schists 65 Chrome and country rocks 128 Chrome in schists 102 Chrome occurrences 132 Chrome ores. 223 Chromite 223 Chry socolla 215 Chrysolite 39 Chutes 81, 204 Cinnabar 11, 212 Claims (See also Locations). Claims, Locating 167 Clay analyse^ 243 Clay, Bowlder 67 Clay, Brick 243 Clay, Fire 234 Clay gouge 79 Clay, Mine 14 Clays 62 Cleat 263 Cleavage 40, 330 Coal..... 259 Coal beds, Faulted 9 Coal, Commercial value 269 Coal, Composition of 260 Coal, Impurities in 266 Coal mines, Creeping 1C Coal prospecting 269 Cobalt bloom 2^5 Cobalt in ocean 107 Cobalt-nickel 132 Cobalt ores 225 Cobaltite. . , 225 Coke tests 268 Colombia, Sulphur in 248 Compact 207 Compass 165 Competition 10 Compression veins 93, 102 Conistock lode. . . .13, 20. 78. 92, 95, 101 107, 109, 111, 112, 113 Concentration 30 Conchoidal 207 Concretionary 207 Conditions, Favorable 19 Conglomerate, Volcanic 66 Conglomerates 60 Contact veins 91 Contacts, Limestone , 94 Contests, Location 195 Copper and country rocks 126 Copper chloride 215 Copper in beds 144 Copper mines, Lake 100 Copper, Native 212 Copper occurrences 131 Copper ore, Testing. 27 Copper ores 212 Copper oxide , 214 Copper-silver 100, 13^ Copper sulphate 213 Copper surface ores 160 Coralline limestone 46 Cornish mines 103, 104, 110, 112 Corundum 236 Country rock and gangue 133 Country rock samples 155 Country rocks and vein filling 120 Country roc us, Effect on fissures. 90 Cracow salt 141 Creeping .' 13 Croppings 72 Cross-cutting 202 Cross-cut tunnels 197 Cryolite 236 Crystal 246 Crystallization of minerals 320 Cubanite 213 Curtis, J. S., on gold and silver in rocks 107 Cuprite 213 Dacite 55 Daintree on gold occurrences 107 Dana on metals in gneiss and granite 107 Dana on nickel in lava 107 Daubree on meteoroids 108 Death Valley 88, 101 Decomposition of ore at surface. . 160 Deep gravels 276 Deposits, Evaporated 143 Deposits, Form of 112 Deposits in limestone 103, 115 Deposits, Mineral sediment 143 Deposits other than veins 138 Deposits, Physical character of. . . 69 Depth, Richness in 159 Derbyshire mines 135 Development 4, 197, 203 Diatomaceous earth 48, 240 Dikes 72,76, 99 Dikes, Lodes on 94, 154 Diorite, Gold in 107 Dip 70, 73, 146 Discharge of water 304 Dolcoath mine 13 Dolomite 47 Dredging 299 Drift mining 291 Drift tunnels 200 Drifts , , 804 376 INDEX. Dry bone Dry washing. Ductile , 217 297 207 E Electro-chemical action 117 Elements 316 Elevator, Hydraulic 297 Elvanite 53 Embolite 211 Emerald nickel 224 Emery 236 End lines 183 Epsom salt 142 Erosion of veins 159 Erythrite 225 Evaporation 139 F Faults 83 Faults in gravels 282 Faults, Reverse 85 Faults, Step 86 Faults, Strike 90 Faults, Trough 87 Feel of minerals 330 Feldspar 37 Felsite 53 Fibrous 207 Filiform 207 Filling of veins , 99 Fire clay 62, 234 " Fissure veins, True 11 89 Fissures 83 Flagstones. : 61 Flaming coal. 264 Flint 46 Float , 162 Floor 69 Fluorspar 237 Folded gravels 283 Foliated 207 Foot wall tunnels 199 Forchhammer on metals in sea water 106 Formations, Succession of 138 Forms of minerals 321 Fragmental rocks 66 Franklinite 218 Eraser river 298 Freestone 61 Frieslebenite 211 Frozen veins 80 Fuliginous coal 264 Furnace Creek 104 Fusibility of minerals 322 G Galena 215 Galena and blende, Separating. . . 26 Galena in limestone 102, 164 Gangue 80 Gangue and country rock 133 Garibaldi mine 7 Garnets 39 Gas coal. . ............ 3 ..... o ..... 264 Gas, Natural 258 Gash veins 86, 95 Geikie on salt in Caspian 141 Genthite........ 224 Geodes 102 Geologic series. 67, 322, 323 Geological Survey, U. S 68 Georgia mines 136 Gersdorffite... 224 Glacial depo its 285 Glacial products 67 Glacier mine '. 114 Gneiss 64 Gneiss and granite. Ores in 107 Gob 205 Gold and country rocks 122 Gold and silver in rocks 107 Gold, Crystallized 101 Gold gravel deposits 271 Gold gravels, Faults in 282 Gold gravels, Folds in 283 Gold in beds 144 Gold in diorite 107 Gold in granite , 102 Gold in sea water 106 'Gold in serpentine 107 Gold in South Dakota 134 Gold, Native 209, 259 Gold occurrences 131 Gold ore. Assaying 24, 25 Gold ore, Free 12 Gold ore, Horning 25, 26 Gold ore, Testing 25 Gold pan 288 Gold, Saving fine 299 Gold, Tests for 296 Gold tellurides 209 Gold veins, Erosion of 159 Gouge 79 Grade of gravel deposits 275 Grade of ore 21 Grand Canon 159 Granite 37, 52 Granite, gold in K 2 Granite, Veins in 97 Granular 207 Graphite 238 Gravel deposits 271 Gravel deposits, Origin of 272 Gravel mines, Clay in 14 Gravel mines, Creeping in 13 Gravel mining 286 Gravel, Faults in 282 Gravel, Folds In 283 Gravel, Testing 296 Gray copper 213 Great Flat lode 112 Gypsum 14, 48, 143, 239 Gypsum in solution 141 H Hammers, Geological 166 Hanging wall tunnels. 199 INDEX. 37? Head Center mine 100 Head of water 304 Heading 204 Heat, Underground 109 Hematite 219 Hillside deposits 283 Horn silver ,100, 105, 211 Horn spoon 25, 165 Hornblende 39 Hornblende rocks, Asbestos in 164 Horses 79, 91 Hydraulic elevator. 297 Hydraulic mining 289 Igneous theory. Illinois mines. . . I 115 Ilmenite 221 Inch, Miner's 302, 309 Incline 204 Infusorial earth 48, 240 Iridescent 207 Iridosmine 212 Iron carbonate 220 Iron-manganese 132 Iron ore beds 143 Iron ore, Bog 8, 143 Iron ores 219 Iron sulphide 220 Isabel mine 105 Joints, Strike 41 Jukes on trough faults 87 Kaolin 62 Karaboghaz salt 141 Keystone mine 93, 112 Killas 103 Lake Superior mines 144 Lakes, Saline 59 Lamination 41 Land prices 195 Lands, Agricultural 172 Lands, Timber 172 Lapilli 66 Laterals 281 Lava 50, 51 Lava cup 278 Lava, Nickel in 107 Lead 72 Lead and country rocks 125 Lead and silver 132 Lead carbonate 216 Lead in Derbyshire 135 Lead in limestone 115, 164 Lead, Native 215 Lead occurrences 131 Lead ore .9, 101 Lead ore in beds 144 Lead oxide 216 Lead sulphate. 216 Lead-zinc 182 Leadville .9, 92, 148 Ledge 72 Leeds mine 105, 144 Levels 204 Light and minerals 320 Lime sulphate 239 Limestone .45, 241 Limestone, Caves in 148 Limestone contacts , 94 Limestone, Coralline 46 Limestone, Deposits in... 103, 115, 164 Limestone, Prospecting in 164 Limonite 219 Litigation 14 Liversidge on gold in sea water. . 107 Locating regulations 189 Location charges 191 Location end lines 183 Location, Final proof of 194 Location length 183 Location notices 175, 176 Location, Publication of 193 Location requirements 168 Locations, Describing 150 Locations, How made 170, 177 Locations, Imperfect 168 Locations, Lode 171, 177, 188 Locations, Making 167 Locations, Placer 170 Locations, Procedure in 191 Locations, Puzzling 185 Lode 72 Lode length 183 Lode line 179 Lode locations 171, 177, 188 Lode locations, Procedure in 188 Lodes, Blind 77 Lodes on dikes 94 Lost vein 6 M Machine washing 295 Magnesite 47, 242 Magnet 165 Magnetite 219 Malachite 214 Malleable 207 Mammillary . . 208 Mammoth cave 115, 148 Manganes^ and country lodes.... 129 Manganese in ocean 107 Manganese-iron 132 Manganese occurrences 132 Manganese ores 221 Marble .. 47 Marcasite 220 Marks, Stake , 173 Marks, Tree 173 Masses 81 Massicot . 216 Massive 208 Matrix. 80 Mary Ann mine 110, 112 378 INDEX. Melaconite 214 Mercury (See Quicksilver). Metacinnabarite 212 Metallic luster 208 Metallurgical experiments 3 Metallurgical plant, Planning 29 Metals and rocks 130 Metals associated with each other 132 Metals, Distribution of 106 Metals, Sp. gr. of 17. 18 Metals, Value of .' 331 Meteoroids 108 Metamorphic rocks. . 64 Metamorphism 42 Metric system. 335 Mica 38, 242 Micaceous , 208 Mill capacity 32, 33 Mill runs 27 Millstones 61 Mine cost and output 16 Mine, Definition of 34 Mine failures, Causes of 14 Mine water 157, 201 Mine, What constitutes a 16 Minerals. Characters of 320 Minerals, Classification of 318 Minerals Cleavage of 330 Minerals, Crystallization of 320 Minerals distinguished according to feel 330 Minerals distinguished according to odor 330 Minerals distinguished according to taste 330 Minerals, External Forms of 321 Minerals, Fracture of 321 Minerals, Fusibility of 322 Minerals, Hardness of 330 Mineral " in place " 172 Minerals, Insoluble 229 Minerals, Qualities Depending on Light of 320 Minerals, Rock-forming 36 Minerals, Separating 26 Minerals, Soluble 250 Minerals, Structure of 321 Minerals, Useful 229 Minerals, Value of 331 Minerals, Worthless 11 Miner's inch 302, 309 Mines, Development of 4, 197, 203 Mines, Unsuccessful , 10 Mines, Working facilities 157 Mining conditions 19 Mining Drift 291 Mining failures 2, 14 Mining ground, Patents to 187 Mining, Hydraulic . . . . . 289 Mining, Mistakes in 1 Mining, Placer 286 Minium 217 Mispickel 221, 225 Molybdenum 227 Mono lake Monte Cristo district 78, 113, Monuments 173, 174, Mother lode 76, 104, 119, N . , mines Nagygite Natural gas Niccolite Nickel and country rocks. . Nickel-cobalt Nickel in lava. Nickel in ocean ..., Nickel ocher Nickel ore Nickel silicate Niter Niter, Chile Niter (See Saltpeter). Notic"s of locations Notices, Posting Nova Scotia schists Obsidian Ocotilla Odor of Minerals , Opals in basalt Olivine Onion Valley dike Oolitic Opaque Ore change at water level Ore, Definition of Ore deposits and country rocks. . . Ore deposits, Form of , Ore, Distribution of Ore, Grade of Ore in depth Ore in limestone 103, 115, Ore "in sight 11 Ore, Origin of Ore, Pockety Ore sampling Ore, Solution of Ore, Source of Ore supply needed Ore deposits, Physical char, of ... Ore thickness Ore tonnage Ores arid rocks Ores, Bulk of Ores from sea Ores, Separating. Ores, Sp. gr. of 17, Ores, Value of Ores, Weight of Orpimen t Otago mines Outcrop Outcrop and springs Outcrop and vegetation Outcrop in location Outcrop, Lesson of the 7, 142 114 181 154 6 210 258 . 224 128 , l&J , 107 , 107 , 224 , 224 . 224 . 254 . 255 , 175 , 176 . 133 . 56 . 152 . 330 . 164 . 39 . 99 . 208 . 208 . 159 206 122 112 12 21 159 164 21 106 6 23 109 111 31 69 153 32 130 18 116 26 18 331 19 226 133 72 153 152 179 158 INDEX. 379 Outcrop of veins 74 Outcrop, Circular 78 Outcrop, Rusty 161 Outcrops of beds 147 Outfit, Prospecting 165 "Overflows," Gravel 281 Oxides of iron 219 Ozokerite 244 Pan , 2 Panning Patents 1&7 Patents, Procedure in 191 Petroleum 257 Petzite 210 Phosphate of uranium 228 Pick, Prospecting 166 Pipe clay 278 Pipes, Water in 304 Pisolitic 208 Pits, Prospect 2( Placer locations 170 Placer mining 286 Plaster of paris 48, 239 Platinum < 211 Plumbago 238 Pockets 6 Pockets, Fault 85 Porcelain clay 62 Porphyry 53, 55, 58 Posting notices 176 Potassinm nitrate 254 Potter's clay 243 Price and profits 20 Prices of metals,ores, minerals,etc. 331 Promoters 4 Prospecting 150 Prospecting and springs 15 f <5 Prospecting and vegetation 152 Prospecting and water system 163 Prospecting for coal 269 Prospecting outfit 165 Prospecting W T hat to look for.... 164 Prospecting Where? 164 Prospect pits 203 Proustite = 211 Psilomelane 222 Publication of location 193 Pumice 243 Pyrargyrite 210 Pyrite 220 Pyrite, Auriferous 27 Pyrite, Decay of 114, 161 Py rolusite 222 Pyrrhotite 221, 224 Q Quartz 37, 243 Quartz porphyry 55 Juarzfte 61 Quicklime 47 Quicksilver and county rocks 129 Quicksilver at Steamboat Springs. 107 Quicksilver for testing 165 Quicksilver, Native 212 Quicksilver occurrences 132 R Ramsay on Bath salts 139 Realgar 226 Reduction works, Plan ing 29 Reduction works, Unsuitable .... 5 Regulations for locating 189 Regulations, Local 171 Reniform 208 Reserves 4, 5, 34 Resinous 208 Reverse throws 85 Rhyolite 35 Ribbon rock 95 Ribbon structure 110 Richmond Con. mine 4 Rio Virgen salt 141 River bars 298 River deposits 274 Roads 29 Rock and gangue 133 Rock names 156 Rock samples 155 Rocks 36 Rocks and metals 130 Rocks, Ohem. precipitated 44 Rocks, Classification of . . . .43, 324, 326 Rocks, Composition of 58 Rocks, Compound 49 Rocks, Crystalline 50 Rocks, Effect on fissures 90 Rocks, Eruptive 133 Rocks, Fragmental 66 Rocks, Influence on vein filling. . . 120 Rocks, Metam orphic 64 Rocks, Organic 44 Rocks, Origin of 44 Rocks, Silicious 131 Rocks, Simple 45 Rocks, Stratified 57 Rocks, Volcanic 66 Roof 69 Ruby Basin 134 Ruby silver 210, 211 Rutile 227. s Salt 141, 256 Salt at Sperenberg 141 Salt in Arizona 141 Salt in Caspian 141 Salt in Cheshire 141 Salt in Poland 141 Salt in solution 141 Saltpeter 142, 254 Saltpeter. Chile 255 Saltpeter prospecting 164 Salts, Soluble, Prospect ng for. . . ie:4 Samples country rock 155 Sampling 23 Sandberger on metals in rocks. . .. 107 Sandstones , 61 Satin spar 101, 239 380 INDEX. Savage mine Schists 42, Sea beach deposits Sea-formed ores Sea water. Metals in , Sediment mineral deposits Segregated veins Selenite 48, Selvage Semi-anthracite Semi-bituminous Serpentine , Serpentine, Gold in Shafts 3, 200, Shafts, Useless Shales Shoots, Ore 81, Siderite Sierra Nevada mine Silicate of nickel Silicate of zinc Silver and country rocks 123, Silver and gold in rocks Silver at Leeds 105, Silver, Brittle . . . . Silver bromide 116. Silver chloride 116. Silver-copper 100, Silver glance Silver in sea water Silver in South Dakota Silver-lead. Silver, Native 101, Silver occurrences Sinking. Sinter Slate 42, 43, Slate Creek Slickensides Smaltite Smelting Smithsonite Soapstone Sodium carbonate Sodium sulphate Solfataric action Solutions, Mineral 109, 134, South African mines South Dakota mines Specific gravity 17, Sperenberg boring Spoon Springs and outcrops Spurs 78, Stakes Stalactitic Stamp, Duty of Stamp mill capacity Stannite Steamboat Springs Step faults Stephanite Stibnite Stockworks 89, 113 Stone monuments 173 65 Stonewall Jackson mine 95, 135 284 Stoping 204 116 Stratification 40, 60 106 Streak plate 166 143 Stream tin 223 95 Strike 70, 74 239 Strike faults 90 . 79 Strike joints 41 262 Strontia 246 263 Structure of minerals 321 49 Stulls 205 107 Subconchoidal 258 201 Submetallic 258 8 Sulphate of copper 215 63 Sulphate of (sad 216 204 Sulphate of soda 256 220 Sulphide of iron 220 101 Sulphide of mercury 212 224 Sulphide of tin ' 223 217 Sulphide of zinc 218 124 Sulphur 247 107 Sulphur Banks 248 144 Sulphurets, Panning 166 211 Sulphurets, Separating 26, 166 211 Sump 205 211 Surface ores 159, 160, 161 132 Survey, Order for 192 210 Surveyor, Authority of 169 106 Surveyor, Duties of 188, 190 134 Surveyor's fees 188 . 132 Surveyors, Instructions to .... 189, 196 210 Sutro 'tunnel Ill 131 Slitter Creek mines 102 200 Syenite .......54, 58 46 Sylvanite 210 , 63 Synclines 146 % T f>25 Tables: ...... 316 29 Elements 316 217 Geologic Series 67, 322, 328 249 Metals, Ores, Minerals, etc., 253 Value of 331 256 Metric System 335 111 Minerals, Characters of 320 139 Minerals, Classification of 318 144 Minerals, Cleavage of 40, 330 134 Minerals, Crystallization of 320 18 Minerals distinguished accord- 141 ing to feel 330 25 Minerals distinguished accord- 153 ing to odor 330 84 Minerals distinguished accord- 173 ing to taste 330 258 Minerals, External forms of 321 32 Minerals, Fracture of 321 33 Minerals, Fusibility of 322 223 Minerals, Hardness of 330 107 Minerals, Qualities depending 86 on light of 320 211 Minerals, Structure of 321 226 Rocks, Classification of.. 43, 324. 326 103 Talc 249 INDEX. 381 Talus 77 Veins not uniform 12 Tape .165 Veins on dikes ..94, 154 Taste of minerals 330 Veins, Opening 157 Tellurides 195, 209 Veins, Origin of , . .83, 96 Tests, U tility of 28 Veins, Pockety , 119 Tests, Working 27 Veins, Richness in depth 159 Tetrahedrite 213 Veins, Segregated 95 Theory-, Aqueous 106 Veins, Thickness of 69, 153 Theory, Igneous 99 Veins, 4k True fissure " 72, 89 Thickness of vein and ore 153 Velocity of water discharge 305 Throw 84, 85 Vesuviau lava 107 Timber rights 172 Vitreous copper 213 Time, Geologic 68 Vitreous silver 210 Tin and country rocks 128 Volcanic products e 66 Tin occurrences 131 w Tin ore 11, 222 Tiusulphide 223 w a ? : 222 Titanic iron 221 Was, False 154 Titanium 227 "WSj vein 79 Tombstone .':.'.'.':.':::.'.".v.'.'.v.Vii6, 157 s***? m i nes 95 ' 113 ' * Tonnage area 17 Water, Bulk of 302 Toimaircafcuiationof:;:::::.8i; 32 Water discharge 304 Tonotrranhv 163 Water in mines 1 57, 201 To?b!rn1?e y :::.v.v.v:.:.v. :;::;::: * water level 159 Tourmaline 39 Water measurement 306 Trachyte 53, 58 Water, Mine 108 TrAnafiiftpnt 2^ Water power 305 TransparentV/.-.V.-.-.-.-.-.-.-.-.-.-: '. '. '. '. '. '. 858 Water P re f re - : * Transpr'taf n of mineral by water 109 Water system and prospecting. . . ua r rm t"> ^7 ** ater, u nit or oO,* Tmna'" " 253 Water, Weight 302 Trough faults'. '. '. '. '. '. '. '. .' .' .' .' .' . .' ." '. .' .' .' .' 87 Waters, Solvent power of 139 -True fissure ve.ns " 89 WMgj^^.^^.;.,...^., 958 TungsVen\\\\\\\'::.v.v:::::::::::: 22? weight of ores 19 Tunnel connections 199 Weirs . J06 Tunnels, Cross-cut 197 West Point, Cal. 102 Tunnels Drift 200 Whea Dolcoath 110 Tunnels in foot or hanging wall... 199 Wheal Mary Ann 110, 112 Tyndall mine '. 78 Wjjjemite |$ U Wisconsin mines 115 Ulexite 251 Wolfram 227 Ulverstone deposits 116 Wood tin , 223 Uranium 228 Working facilities 157 y Works, Planning , 29 . Works, Unsuitable 5 Valuation of mines 20 Values of metals, ores, minerals, Y etc 331 Yale 298 Vanadium .'?? Yankee Hiti.' .'.'.'.'.'.'.'.'.'.'. '.'.'.'.'. '.'.'.'.'.'. 101 Vegetation a guide in prospecting 153 Yellow Jacket mine 109 Vein, Area extracted 33 Yucca... 152 Vein, Distance traceable 151 ........ Vein filling 99 *- Vein matter 80 Zinc and country rocks 127 Vein structure 6 Zinc at Altenberg 116 Veins, Blind 77 Zinc carbonate 217 Veins, Compression. 93, 102 Zinc occurrences 131 Veins, Contact 91 Zinc ores 217 Veins, Definition of 72 Zinc oxide 218 Veins, Frozen 80 Zinc silicate 217 Veins in granite ". 97 Zincblende 218 Veins, Measuring 153 Zincite 218 Veins, Narrow 6 Zinc-lead , . , , 133 'AN INDISPENSABLE REFERENCE ANNUAL.' THE MINERAL INDUSTRY, ITS STATISTICS, TECHNOLOGY AND TRADE IN THE UNITED STATES AND OTHER COUNTRIES. EDITED BY RICHARD P. ROTHWELL. Vol. I. From the Earliest Times to the Close of 1892, - $2.50 Vol. II. Supplementing Vol. I, " " " 1893, - 5.00 Vol. III. Vol. IV. " Vol. V. ' Vol. VI. " Vol. VII. " Vols. I and II," " 1894, - 5.00 Yols.I,IIandIH," 4 1895, - 5.00 Previous Volumes, 4 ' ' 1896, - 5.00 (( U U ' 1897, - 5.00