MAIN LIBRARY TN 550 J6 ft. h tn-_ - J -~1 REESE LIBRARY UNIVERSITY OF CALIFORNIA. ^cessions \'o. ' PRACTICAL MINING AND ASSAYING BY FREDERIC MILTON JOHNSON PRICK ONE DOLLAR SAN FRANCISCO PUBLISHED BY THE AUTHOR 1897 O COPYRIGHTED, 1897 by F. M. Johnson. Certificate No. 32408 C 2 PREFACE. This work is the result of fifteen years of prac- tical experience in the mountains, the mines, the mills and the assay office, and is published for the benefit of the prospector, the miner and those who may desire to obtain a general knowl- edge of practical mining and assaying. I have endeavored to make it as brief and plain as possible for those who have not had the opportunity to acquire the desired information on this subject, and this alone has prompted the publication of this pocket edition of PRACTICAL MINING AND ASSAYING. FREDERIC MILTON JOHNSON. ERRATA PAGE 29: Fourth line, use Sulphuric acid instead of Muriatic acid. PAGE 50: Third line, after the word "with" add the word "water". CONTENTS. Assaying page 33 Assay for Pure Concentrates 49 Amalgamation . 55 Bead Scale 39 Chlorination : 59 Cupellation 38 Concentrator 53 Chemical Assay for Gold 27 Dressings for Different Ores 44 Dressing the Plates 56 Formation 11 Fluxes 41 Glossary 99 How to Keep Mercury 56 Introduction 7 Leveling Instrument 65 Measuring Inaccessible Distance 62 Measuring Inaccessible Distance, (with in- strument) 67 Metals that are Dissolved in Acids 49 Milling Test for Free Gold 26 Mining Laws 90 Ores (see rocks) Panning for Gold 32 Parting ' 38 Preface 3 Pulp Scale 35 Rocks 12 Sundry Items 68 6 PRACTICAL MINING Tables, Assay Table, (240 grains) 73 Assay Table, (20 grammes) 76 Cast Iron Pipe 83 Natural Sines 84 Pelton Water Wheel 89 Relative Value of Weights 81 Specific Gravity, Weight and Melt- ing Point 80 Wrought Iron Pipe 82 Test for Arsenic 31 Black Zinc Blende 20 Fluorspar 30 Gold 26 Gold (with gunpowder) 28 Iron 26 Gypsum (heavy spar) 31 Lime and the Carbonates 30 Lime, Magnesia and Barita 31 Manganese 29 Mercury (cinnabar) 30 Nickel 25 Nitrates (chilly nitre, etc.) 32 Red Copper 29 Silver . 24 Tellurium 31 Zinc 29 Testing Ores with Acids 50 Veins or Lodes 21 Weighing .40 Wet Assay 25 INTRODUCTION. Carbon is the base of the vegetable and organ- ized world, and quartz or silica is the chief or principal of the mineral world. A particle of any one substance is a unit or simple. There are 64 simple substances known. Those that are un- known are termed elements, which have a tend- ency to combine with know substances or other elements, forming compounds with the different substances under various conditions of tempera- ture, pressure, electricity, etc. All may assume either a liquid, solid or gaseous state. These elements may be mixed in any proportion, but they combine only in fixed proportions. Chem- istry gives us the knowledge of the proportions in which the different substances combine. A general idea only of such knowledge necessary for this work is given. The mixture of all metals by fusion forms alloys, hydrogen, oxygen, chlorine, bromine, sulphur, arsenic, phosphorus, silicon, etc., with the different metals enter into the various compositions of ores and fluxes, which to a certain extent the assayer must understand. A test of ore is made with acids or heat, usu- ally with a blow pipe, with an indefinite amount 8 PRACTICAL MINING of ore, simply to determine whether the ore con- tains gold or silver or the metals sought for. Testing may precede assaying to enable one to know what fluxes are best adapted for a correct assay. Assays are made by wet or dry processes, i. e., acids and chemicals or heat with the proper fluxes and with a definite quantity of ore to de- termine the exact amount of metals it contains per ton of ore. Lead combined with oxygen in the exact proportion of 103^ parts of lead by weight to 8 parts by weight of oxygen to form litharge, this being a flux for most classes of ores carrying precious metals. The melted lead gath- ers up the precious metals and is thrown down by carbon which is a reducer, forming a lead button in the bottom of the crucible. Under heat the affinity of carbon for oxygen is greater than that of lead for oxygen. Therefore if lith- arge and carbon are heated together the carbon takes the oxygen from the litharge and the lead is set free and. goes to the bottom as stated above. One grain of charcoal reduces 30 grains of lead from litharge. Flour contains carbon and hydrogen, also oxygen and nitrogen and conse- quently is a reducer, but one grain of flour will only throw down 14 grains of lead. Hence double the amount of flour must be used in an PRACTICAL ASSAYING 9 assay. I prefer the flour for assaying because it is more convenient to procure and is cleaner and in a finer powder. Nitre consists of nitrogen, oxygen and potas- sium, and when heated gives off its oxygen. When sulphur is present, the oxygen combines with it, and the sulphur is carried off, because the affinity is stronger for the sulphur, so that nitre is used in the assay of sulphurets to carry off the sulphur, melted lead having a strong affin- ity for oxygen which it takes from the air, when the door or opening to the muffle is open to admit it and the lead is oxydized and part of it goes off in fumes and part is absorbed by the bone-ash of which the cupel is composed. Gold and silver do not combine with oxygen, hence when the lead button is cupelled, the gold and silver remain. OF THR A UNIVERSITY ) FORMATION. This question is of the utmost importance and requires considerable study, but a general idea may be given to help the miner or prospector in his search for gold, and requires a technical knowledge of mineralogy. By technical miner- alogy I mean only that amount of mineralogical knowledge which will enable the prospector to recognize the valuable minerals and metals and to trace them by the formation in which they are most likely to be found. This forms but a small part of the whole subject of mineralogy as a sci- ence. It is therefore important that the prospec- tor should be able to distinguish many kinds of rocks, to guide him or to check him in his ex- ploration. The formations forming the gold belts are en- tirely different in different countries or districts, hence the knowledge of the formation in Oregon or Arizona will not assist the prospector in Cal- ifornia or any other territory except in a very general way. A man may be an expert on the Mother Lode in California and know nothing of the formation in Colorado. One thing, however, may be settled for any country or district, and that is where veins, lodes, or vein matter is 12 PRACTICAL MINING found in a contact or fissure, i. e., a vein between adjacent bodies of dissimilar rock, where gold is found in these formations it is the very best evi- dence of the existence of a permanent ledge, and the prospector can begin his development with a certain degree of certainty. ROCKS. Rocks may be classed in four great groups, described as follows: Superficial rocks, Sedi- mentary rocks, Igneous rocks and Metamorphic rocks . FIRST THE SUPERFICIAL ROCKS. These are composed chiefly of clay, sand and gravel and lie in irregular beds and unconsolidated. SECOND SEDIMENTARY ROCKS. These are conglomorate sandstone, shale and limestone which have been deposited by the water and have usually become hard. THIRD IGNEOUS ROCKS. These are rocks w r hich have been thnrvvn up from a molten con- dition through crevices and fissures and cooled where they have formed dikes and veins. Some- times they pour out of cracks and volcanoes and flow over the surface as lava and afterwards be- come scattered and broken up by water and PRACTICAL ASSAYING 13 streams. The most abundant of these are gran- itic, grano-diorite, granite -porphyry, diabase, basalt, augite-porphyrite, augite-andesites and hornblende. FOURTH METAMORPHIC ROCKS. These are altered rocks of crystalline texture and have been so changed by pressure and chemical action that the mineral particles in many cases re-crys- tallize and are understood as metamorphic, crys- talline formations. We will now give the names and a brief des- cription of some of these rocks. ALLYBYDENUM is a sulphide in masses. Has a strong metallic lustre. Color, dead grey. Shows a greenish black streak on a common piece of broken plate or china. Easily scratched with a nail. Occurs in granite, syenite and chlorite schists. Sometimes mistaken for graphite. Its chief use is for the manufacture of blue colors. Value, $12 per pound. ANDESITE. An effusive, porphyritic rock. The constituents are lime, spar, magnesia and silica. ANTIMONY. Resembles galena in color but is crystalline in form and when pure looks like a mass of needle points melted together. Very often galena and antimony are combined, espe- 14 PRACTICAL MINING cially iii gold and silver ores. This metal mixed or combined with galena often destroys the value of a lead mine, and vice versa. AUGITE. A dark green or blackish, composed of iron, schists, and magnesia; lustre vitreous; found chiefly in volcanic rock. BASALT. 40 to 50 % of silica, 15 to 30 % of alumina, and oxide of iron, manganese, lime, and magnesia. Color is black, bluish or greenish shades when broken, usually drab or greyish brown on the surface. BIRD'S EYE PORPHYRY is composed of feldspar and specks of hornblende and mica through the rock in such a manner as to form little specks resembling birds' eyes. CASSETERITE or TIN ORE. Tin ore is usually an oxide and contains small quantities of iron, copper, manganese, arsenic and silica and rarely any lime. The ore is nearly as hard as quartz and will scratch glass. It is of a dark brown color, sometimes almost black; when scratched with a file or knife, the mark turns brown or light brown. Zinc does the same when found in other ores. These are the only metals that the fine powder made with a file turns brown. It is usu- ally found in granite, quartzite, metamorphic sandstone and slaty rock; often traced with black ^ PRACTICAL ASSAYING 15 tourmaline. It is sometimes found with other ores as the sulphide of tin with iron and copper. Looks like bell metal or black oxide of tin. It is found in granite only when the granite con- tains chiefly mica and quartz or mica and soda feldspar. COPPER GLANCE. Similar to the above in character but carries a much larger per cent, of copper. The fine glance carries about one-third metal. Found in copper ores. DIABASE. An intrusive or effusive granular rock composed of augite, partly or wholly con- verted into fibrous hornblende, soda, lime and feldspar. DIORITE. A granular intrusive rock com- posed piincipally of soda-lime, feldspar and hornblende. FELDSPAR is silicate of potash and alumina; silica and lime. GABBRO. A granular intrusive rock consisting principally of dialage, pyroxene, together with soda, lime and feldspar. GABBRODIORITE. This term has been used where the gabbro areas contain primary and secondary hornblende. GALENA. Bright lead color having a metallic lustre and when not mixed with antimony, 16 PRACTICAL MINING breaks in cubes; carries silver and gold; very often found in gold ores. GRANITE. A term descriptive of rocks com- posed of silica, feldspar and mica. There are different classes of granite, nor are they alike in color. Some granites contain no mica as in graphic granite. Others contain black mica stained with iron, and hornblende. GRANO-DIORITE. This is also an intrusive rock carrying feldspar, quartz, biatite, horn- blende and mica. GRAPHITE or PLUMBAGO or BLACK LEAD. Soft and soils the fingers; marks on paper; color, gray to dark blue, nearly black. Found chiefly in crystalline limestone and mica schists or graphite schists. GYPSUM. Composed of sulphuric acid, lime and water. When it is pure white it is called alabaster; when transparent, selenite; when fibrous, satin spar; and when burnt, forms plaster of Paris. HORNBLENDE. Contains dark or black crys- talline specks or crystals consisting essentially of silica, magnesia, lime and iron. ITACOLUMITE. A quartzose rock that is more or less cemented by mica; takes its name from a mountain in Brazil. Diamonds and other pre- PRACTICAL ASSAYING 17 cious stones are found in this and other similar rocks. KAOLIN. A peculiar clay, composed of silica, alumina, pyroxide of iron and water. It is used in the manufacture of porcelain and china; found in granitic formations. LIMONITE. A brown ironstone. It is com- posed of iron, alumina and silex-, and sometimes manganese. Belongs to the iron ores. MANGANESE. It occurs as a black or red ox- ide, often with red or brown hematite; very easily pulverized. When dissolved with muriatic acid, it throws off chlorine gas which can be easily detected by the smell. MICA SCHIST. This term is given to those laminated rocks composed of mica and quartz, manganese, often black, colored with iron, easily broken up. MISPICKLE. Often mistaken for brittle silver. It occurs usually in ores that are regarded as re- bellious with zinc and other bases. It is simply composed of arsenide of iron and iron pyrites and is very brittle. MICACEOUS" QUARTZ ROCKS. These are not very common. Generally found in a granite formation; sometimes carry gold. 18 PRACTICAL MINING PORPHYRY is feldspar, quartzite, talc, mica, iron, and clay; chiefly feldspar and quartzite. PORPHYRITIC GRANITE. A granite with a large proportion of porphyritic potash-feldspars. Color, dark green. PORPHYRITIC QUARTZ. A rock consisting of quartz, lime, feldspar, and a small amount of hornblende. Often found in contact or con- nected with grano-diorite. PYROXENE. Lustre vitreous inclining to res- inous, some pearly. Color green of various shades verging from white and grayish white to brown and black. A bi-silicate of lime, magne- sia, protoxide of iron, protoxide of manganese, and sometimes potash, soda and oxide of zinc. Usually tw r o of these bases are present. The first three are the most common but l ; me is al- ways present and in a large percentage. QUARTZ or SILICA is combined with nearly every other kind of rock. The miner must study it carefully, as nearly all the gold is found connected with it in some way. A few general ideas may be given to assist the prospector. When found in ledges or loads in granite walls, it is flinty and white when pure, but it is nearly always stained with iron and often car- PRACTICAL ASSAYING 19 ries iron pyrites. It breaks in chunks like sand and granite rocks, and when gold bearing, the gold is found in pockets or bunches and not evenly distributed through the rock as it is found in other formations. Sometimes laminated or stringer quartz is found in granite that carries the gold principally in the seams. When found in a contact vein or "true fissure" it is of a more even texture, carries lime and spar and is much the better class of ore. When gold or pay ore is found, it is more evenly distributed through the quartz when found in contact of slate and por- phyry. It carries enough oxide of manganese or slate to give a bluish cast, and is more stratified. Often carries iron pyrites and galena, and when galena or copper stain is found in the quartz, it is the best evidence of a permanent ledge of ' 4 pay ore." This class of ore when found in Mexico, Arizona, Nevada and Southern California, car- ries silver and often leads into a silver mine be- low the water line. RHYOUTE. It is of the tertiary age. The essential composition is alkali, quartzose, and hornblende. RED OXIDE OF MANGANESE. Looks like red ironstone. At first sight might be taken for cinnabar. 20 PRACTICAL MINING SERPENTINE. A hydrous silicate of magnesia combined with talc, syenite, and hornblende, forming rock known in mining regions as ( "ser- pentine." SIDERITE. An iron carbonate; about 62 per cent, of protoxide of iron or nearly 45 per cent. of pure iron and from 15 to 20 per cent, of man- ganese. Looks like black ironstone with snail streaks or specks of white. Color, gray to black. SILVER occurs native in various forms usually branching or leaf-like or in small particles that resemble leaf lead. " It is never found pure; often carries copper, lead and gold; it is always malle- able and can easily be distinguished from mis- pickle by the fact that it can be cut with a knife and is not brittle. Before the blowpipe it melts without leaving any oxide or whiteness around it as does zinc, antimony, bismuth and tin. SILVER GLANCE. A metallic silver combined with iron and copper. Has the appearance of leaf lead nearly black. Often occurs pure enough in the ore to be cut with a knife. This is often connected w r ith copper glance found in rich cop- per ores with hematite. Usually carries from 20 to 33 per cent, of silver. SLATES. There are several kinds of these slates which should be carefully studied. All of PRACTICAL ASSAYING 21 these slates are sedimentary or water washed dis- integration and are found as mica slate, horn- blende slate, clay slate or argillaceous shale and bituminous shale, plumbago schists and talcose slate. Sometimes trap rock and trap and blue limestone are mistaken for slate, but all slates have cleavage lines and break in planes while the trap rock breaks irregularly and rough and rings to the hammer. TALC. Composed chiefly of silica and magne- sia, with alumina and iron; color varies from a greenish, to a yellowish white with a pearly lus- tre, and is smooth and greasy to the touch, or soapy if moistened. ZINC BLENDE. Streaks white to reddish brown. Color, resin yellow to dark brown or black. Occurs in rocks of all ages and is often associated with ores of lead and sometimes those of iron, copper, tin and silver. VEINS OR LODES. The rocks in the Auriferous Belt occur in very complex associations, but we have to deal prin- cipally with the granites, slates and schists, and it is chiefly in these schists that the gold or quartz veins are found. These "gold belts" 22 PRACTICAL MINING consist principally of quartzite, mica-schists, clay, slate and limestone lentils. The trend of these lodes or belts is generally North-west and South-east, but the great mass of granite and igneous rocks have been intruded among these schists, forming irregular bodies which interrupt the regular schistose structure, These are of the group that forms the famous "Mother Lode" of California. Converging or wedge veins are numerous and lie between the divisions of stratified rock, as granite, clay, slate, etc. They are never very long and sometimes show a large blowout or cropping, but are nearly always unreliable, as the wedge-like space between the walls must neces- sarily diminish in depth. GASH VEINS. These are found in all sedimentary deposits. They are caused by shrinkage of the particular stratum in which they exist by the underlying igneous conditions. Ledge matter or mineral deposits may be found in these veins which sometimes "go down" to quite a depth and may be rich, but they are not very long and thin or pinch out at the ends. Sometimes they are lapped with another similar vein which may con- PRACTICAL ASSAYING 23 tinue further. A number of these veins may lap each other and form a number of ledges in one claim only a few feet apart, but they seldom, if ever, go down to any great depth or make a large or permanent mine. FISSURE VEIN. True fissure vein quartz in- variably shows ribbon-like stringers parallel to the walls. The most lasting and permanent pay- ing mines are found in true fissures as well as in the contact. CONTACT VEINS. A quartz ledge or other vein matter lying between two walls of dissimilar rock, as slate and porphyry, or granite and dio- rite, etc. CROSS VEINS are transversely fractured fis- sures of more recent origin. They are often pay- ing feeders for the mineral deposits of regular veins. BLANKET LEDGES are those that lie nearly horizontal and are often a break from some per- manet vein that may be found in slides which have moved them from their fracture. They are seldom very large. DIKES are not veins and are generally larger and are chiefly composed of yellow or blue col- ored feldspathic, finely crystallized, igneous rock, or porphyry, often carrying gold, but very fine. 24 PRACTICAL MINING DEPOSITS. Sometimes quite extensive and must have been concentrated by alluvial water- washing, or precipitation of quantities of min- erals in large cavities or depressions in the bed- rock. Those of the volatile and condensable minerals found in these deposits are cinnabar and sublimations of lead and antimony. ALLUVIAL DEPOSITS are of placer and gravel, sometimes rich in gold and platinum. QUARTZ LODES and vein matter often well defined, and cropping boldly in veins and spurs, cross-courses and small dikes, with a variety of heave, shift or slide that are very misleading and must be carefully studied and examined in order to determine what relation they bear, if any, to a contact or "true fissure." TESTS. TEST FOR SILVER. Powder and boil a small quantity of the ore in nitric acid; allow to settle and put in a few drops of muriatic acid when it will immediately form a white curdle if silver is present. When exposed to sunlight for a short time, this white curdle will turn dark. Sometimes the whole solution is colored with iron; if so, allow it to stand in PRACTICAL ASSAYING 25 the test tube until the whitish curdle will settle in the bottom as a precipitate. TEST FOR SILVER IN COPPER ORES. Boil in nitric acid as above; allow it to settle. Put into the soluton a polished piece of copper. If silver is present, it will show on the copper. WET ASSAY FOR CpPPER. Pulverize an ounce of ore finely; place in a pint dish (agate or porcelain lined) and boil in four ounces of muriatic acid until the acid has nearly all evaporated, leaving the mass in a pasty condition. Add one-half as much sul- phuric acid and boil and stir for a few minutes. Then add five times the quantity of water. Stir until it nearly boils, then filter the whole. The copper is now all dissolved and held in solution. To this solution put in about four square inches of sheet zinc and allow it to stand until the zinc has entirely dissolved. All the copper will be precipitated in the form of a brown or nearly black powder. Filter and dry when the powder may be weighed and melted into a button. TEST FOR NICKEL. First pulverize one ounce of ore. Boil in 3 ounces of muriatic acid until nearly dry. Add 8 26 PRACTICAL MINING or 10 ounces of water; stir and boil. Filter and add to the solution caustic potash until it stops effervescing. Filter and put the filtrate in a cru- cible with three parts of soda and one of borax, and melt. Allow it to cool in the crucible and find the button in the bottom. TEST FOR IRON. Powder and dissolve in muriatic acid in test tube over the lamp. Allow it to cool and settle. Add a few drops of ferro-cyanide, when, if iron is present, it will immediately turn blue. TESTS FOR GOLD. MILLING TEST. This may be satisfactorily made in the following manner. Break up and powder the ore to pass through 10 mesh, not less than one-fourth of a pound: one or two pound lots are better if your muller or mortar is large enough. For this purpose a Buck's patent muller is the best. Now dissolve one ounce of cyanide and 3 ounces of caustic soda in five gallons of water: then add one-half teacup full, no more, of this solution into the water or muller with the ore, and half a thimble-full of mercury, then add one pint of water; grind for half an hour; fill the mortar nearly full of water, turning slowly for fifteen minutes. Empty the whole in a pan and PRACTICAL ASSAYING 27 collect the mercury. Be careful to save every particle. Sometimes it is very hard to collect all of the mercury. In such cases pour off all the water and add a little sodium amalgam; shake for a few minutes, when it will all collect nicely. In the absence of sodium amalgam use one hand- ful of dry sand, stirring it thoroughly for a few minutes, then pan it as usual, when the mercury will collect. Now dry the mercury with blot- ting paper, put it in an evaporating dish or any small dish that will stand heat; cover with two ounces of nitric acid and boil until all agitation ceases. The gold, if any, will be found in a bead-like form at the bottom. Pour off the acid carefully, rinse with rain or distilled water; dry over a lamp and weigh. Calculate the weight of gold at four cents per grain. If one pound of ore has been used, multiply by 2,000. If one-half pound of ore, multiply by 4,000, and so on. This gives the value per ton. Follow these di- rections carefully and the result will give the exact quantity of free gold. CHEMICAL ASSAY FOR GOLD. Take a carefully prepared sample of one ounce of ore, ground to 60 mesh; put into an enameled or porcelain dish with a half teacup-full of nitric acid; stir and boil until the fumes are steam PRACTICAL MINING white. Now fill the dish with clear water, stir and then filter, or carefully pour off the water; add a little lime or lye with more water to entirely destroy the acid. Be sure to save all the pulp, filter or pour off the water again; rinse all the pulp into an earthen bowl; now add a few drops of mercury and grind with a pestle or the bottom of a long bottle for half an hour, save the mercury and retort with acid as in the mill test. Weigh and multiply by 32,000; the result will be the value of a ton of ore. The gold from this test must be weighed on the bead scales. One bead point on the scale with one-tenth of a grain rider is equal to $12.56 per ton of ore. A TEST FOR GOLD. A simple test for gold may be made by first pounding the rock to a fine pulp and mixing with it twice the quantity of common gun- powder and water into the constituency of thick mortar. Press it into the form of a brick or ball and let it dry. When thoroughly dry place it on a shovel or flat rock, cover with a few chips and set fire to it. When the fire goes out, rake through the ashes or pan them, and you will find a gold button if there is any in the ore. This test will not succeed if the ore carries much iron pyrites or other base metals. PRACTICAL ASSAYING 29 TEST FOR MANGANESE. A very interesting test for manganese is made as follows. Take the ore supposed to contain manganese and powder a little very fine and dis- solve it in ^KMTattc acid over a gentle heat; then let it cool and settle. This solution will be col- ored brown. Now dissolve a little sal soda, (common washing soda), in pure water; then put a little of the brown solution into a test tube or saucer, add soda solution, when it will instantly become clear and nearly water- white, if mangan- ese is present. If curdled and dark or cloudy, it is iron, and not manganese. TEST FOR RED COPPER. Very brittle; does not froth with acid, but is dissolved in ammonia and turns blue in a few minutes. Also the carbonates of copper will turn blue when dissolved in ammonia. TEST FOR ZINC. Powder the ore and throw on live coals. Shows a brilliant white flame. Moisten a piece of charcoal with a solution of cobalt nitrate. Put some of the powdered ore on the moistened char- coal and heat with a blow pipe or over the forge, when it will turn to a deep green. 30 PRACTICAL MINING BLACK ZINC BLENDE. Is sometimes found so pure that it is mistaken for galena. The infallible test is that when scratched with a knife the powder of galena turns black whilst that of the blende turns brown. TEST FOR FLUORSPAR. Is composed of fluoric acid and lime. Throw a piece" in a hot fire on a forge, when it will fly and crack in pieces. The pieces of the pure fluorspar after a strong heat will show a phos- phorescent light some little time after being taken from the fire. Once seen will always be remembered. TEST FOR LIME AND THE CARBONATES. After heating to nearly a white heat, will slack in water and w r hen powdered produces a some-* what violent effervescence in acids. TEST FOR MERCURY. (CINNABAR.) Powder the ore, mix one or two grains with equal parts of soda, and place in the bottom of the test tube. Take a small thin piece of copper or brass about two inches long or a little gold- leaf; (the gold leaf must be wrapped around a thin piece of wire.) Place the copper inside the test tube using a cork to hold it in place one PRACTICAL ASSAYING 31 inch of the copper extending below the cork. Gently heat over a lamp until nearly red and allow it to cool. If mercury is present it will show on the copper, brass or gold, whichever may be used. TEST FOR TELLURIUM. Powder and moisten ; heat with blow pipe on a piece of white porcelain; now" moisten the hot porcelain with sulphuric acid. Leaves a red or scarlet color. TEST FOR ARSENIC. Powder the ore and throw on to coals or heat on charcoal with a blow pipe. Gives off the smell of garlic. TEST FOR LIME, MAGNESIA AND BARITA. It cuts or scratches with a knife. Foams or effervesces with nitric acid. It dissolves with effervescence in muriatic acid, and if pure, that is, not mixed with other matter, the solution will be colorless. TEST FOR GYPSUM. (HEAVY SPAR.) Is scratched with quartz or a knife. Does not dissolve with acids and has no smell when heated. When ground finely, it feels like starch. 32 PRACTICAL MINING TEST FOR NITRATES. (CHILLY NI- TRE, ETC.) Flashes when thrown on live coals. It will dissolve in water, and when four parts of this so- lution and one part of sulphuric acid and one part of salt are mixed together it will dissolve gold. PANNING FOR GOLD. The prospector and even the practical miner is almost invariably deceived in the value of gold he gets from a few pieces of ore in the pan or horn. In the first place, he will always think that the piece or pieces of ore he took to sample or pulverize is not nearly as much as it really is. He will think he has pounded up about an ounce when it is nearer three ounces, and should al- ways weigh the sample before crushing, and then he may form some reasonable estimate of the value of ore per ton by the amount of gold in the pan, if he has been careful to have even ounces, as two or four. Now after he has saved a few colors they always look to be more than there really is. Especially if the gold is fine, one may really think there is $10 per ton when there is not $5. It takes very many fine particles of gold to make one cent. To illustrate how very PRACTICAL ASSAYING 33 fine it can be, one grain of gold is worth four cents, and this one grain can be hammered into a leaf of gold containing 75 square inches. One 50,700th part of one grain can be seen by the eye, and gold is found in talcose slate so very fine that it would take enough of these par- ticles to cover four inches square to make one cent, so unless the gold is coarse, one may easily be deceived as to the amount or value of gold in a ton of ore, if you will carefully pan the gold from ^ pound of ore and then collect it with mercury, as in the mill test given on page 26; then the gold can be weighed and calculated with some degree of certainty. ASSAYING. This work is not intended for those who wish to fit up an assay office for a permanent business, in which case they would require a full and com- plete laboratory. I will endeavor to describe and explain how to make satisfactory assays and prac- tical tests on the ground, at the mine, or over the forge. An outfit for the assay er may be very elaborate and expensive but for the purpose of this work only the few implements actually necessary are mentioned. First, a small port- able carbon or coke furnace. It can be bought for $12 or $15. In a coal furnace the muffle will 34 PRACTICAL MINING be included. With the carbon furnace it will be necessary to have a muffle furnace separate. This muffle furnace will cost about $23, but for the many w r ho may not possess either of these, satisfactory assays may be made with an ordi- nary blacksmith's forge. Nearly everything re- quired for practical tests and assays may be had at almost every small town, or may be carried in a gripsack. The only expensive things required are the scales for weighing the prills or beads. There are small pocket scales that will answer every purpose, and can be bought for $12, but if one has no scales, the prills or beads from the assay and the gold from the, mill test must be saved in small bottles, and numbered, to be weighed when convenient. For assaying one must have crucibles to hold 8 ounces. I use No. 9 Denver; they cost 8 cents each. (Following is given a list of the more im- portant things.) The cupels should be one and one-half inches, and cost 30 cents a dozen. One-half inch test tubes 5 inches long. For a drying cup a broken saucer will answer. Evaporating dishes 3 and 4 inches. These cost 35 cents, and will stand heat. A muffle costs one dollar. A substitute for a muffle. Take a piece of 4 or 5 inch 'iron pipe or an old mercury flask or a PRACTICAL ASSAYING 35 crucible; any one of these will answer the pur- pose. A mortar. A good substitute for a mor- tar is a piece of 2 or 8 inch gas pipe 8 inches long. For a pestle any old steel drill. Sieves 6J mesh and 10 mesh. One pair of small pulp scales to weigh the ore; any scales that will weigh a half-ounce or more, will answer. On page 36 is a cut of a pulp scale that any one can make in an hour, that will answer for weighing from one-sixteenth of an ounce to two ounces or more of ore for assaying. A glance at the cut will show how it is made. A scale bar is made out of a thin strip of board \ inch wide, narrowed down at the ends a little, and a needle put through the middle just above the center line; piece of tin, 3 inches long and 1 inch wide, more or less, with the ends bent up square, as shown, for the needle to rest on; and the cover of a small tin can be fastened to one end to hold the ore, and a small bar of lead weighing just two ounces, bent so as to straddle the bar. Place the lead weight close to the needle, just so it will balance the pan at the other end. Mark the bar at the lead, and divide or rule it from the bal- ance to the end into 32 lines or divisions, to the end. Now when the lead weight is at the end it should balance with 2 ounces of ore in the pan. 36 PRACTICAL MINING CO vi E_- CQ <^q <^> Q Q c^ . GO ^JLOOTHOiOOOTH 00 O -O5THt>-?O CD OO s= TH TH OO CO 00 1C (Mt^t^(MOC- -i 1 O O5 t*" CD ""^ COOOOOOOC^C^Oi^THTH C^ C<1 OO *C OO *C O5 CD l>- OS CD OOOOI>'C^t^COCO" 1 ^ r '^ ; IOO OO O5 !> TH CO < CD S _C3 O 73 a s S a !-! tO 2 G C3 -i ^ ae I w i ; H' ri O | J . : J J PQPQOOrHl-4^P-lOQ^H^ PRACTICAL ASSAYING 81 SK tOM tO M M -J i-" O *- SO 00 -J C5 M ' ' ' sa. o ,fo OM SS o E 5! .g S f3 S 3 o 5 ot 3 M\(i\kKli\M\M\lfi\M\ 9 o c* 1 1 1 1 ^3 \ \ \ \ K^S^^^OCn^^tOM (h o ^4 M> M M 8 O 90 u * I o I!!! at _x i i ! ! coi-orf>.iccoooc>oicotc tn O 1 03 M r 1 > hH < w > d w o cJO O^ cr- 3 > i CO- > Jz{ U ^ ^ O S Q 82 PRACTICAL MINING a ^, bfl W 1C J! = *2 M .,- I S s 3 c i w ES gfii 2 giii , $t H j< CCi v.^2 s ift -4 rH iH -N Si * .28- 151 ssg "^ O l^- "^ 1C O i-^ rH O ^ 1C C5 rH CC O i* C^J ' ~ ' > ~ '~ " '- ; *. ~ 1 -^ ^ T ; 'C. I ^ "-^ 'M ^- CT. O Ct rl X Tf Tf -o ut 02 Cl T* rr I- I- 1 c; r' o * so c- IN IM' I-H ' r-J T-i i-i r-i N 00 CS O PRACTICAL ASSAYING Size Inside Diameter. 0*0 E8U && 8,?8 ittft |SS' SI I CT>O> ( 12881 Thick's ot Metal. Weight per Length. Thick's of Metal. Weight per Length. * 3 S3 3 N5, n f- 4 r* Ift | Thick's of | Metal. ^Weight per Length . Thick's oi Metal. tO tOM M l-> ?! !| O 9 ? B n > C" CO . tC O Weight per Length. Thick's of Metal. Weight per Length. Thick's of Metal. Weight per Length. Thick's of Metal. Weight per Length. X3 ^ o a^p ? PH O CO Contents in galons for 1 ft. in Length. I w O 84 PRACTICAL MINING TABLK OF NATURAL SINES. De- () , gree. j U 10' 20' 30' 40' 50' .0000 .00129 .0058 . U087 .0116 .0145 1 .0175 .U2U4 .0233 .i)2li2 .0291 .0320 2 .03-19 .0378 .0407 .0436 .0465 .0494 3 .05:23 .0552 .0581 1 .1.010 .0640 .0669 4 .0698 .0727 .0756 ! .0785 .0814 .0843 5 .0872 .0901 .0929 .0958 .0987 .1016 6 .10-15 .1074 .1103 .1132 .1161 .1190 7 .1219 .1.248 .1270 .1305 .1334 .1363 8 .1392 .1421 .1-149 .1478 .1507 .1536 9 .1564 .1593 .1622 .1C>50 .1679 .1708 10 .1736 .1765 .1794 .1822 .1851 .1880 11 .1908 .19:i7 .1965 .11) 5 55, s v EG 7 > 5 s W. - -o x S y j 5? ^s^ fl 1 1 is a -4-* QJ 3j ?. a tJ i-i-i 1^^^ 1 il g & s5i^ 2S?2^ r-ic5U3 C | , S?3 ^..| ssi 3sS 3S Horse Power Cubic Feet-- Miner's Inch Revolutions. i i i !!i is:: s.afc| tS a > S3SS PRACTICAL ASSAYING 87 s SRWSKffB < 3 o*-t < 3 cr-i 2.qs-S 2-qS'S C ,J* hrt . , ^ r*T M . Po Fee 's I tio OiOO CO i*>.b 1C CC 23 Power eet s Inches tions co K ft *- o < 3 0*_i o'm Pow Feet er's Inc olution - 5 t*. C5OO ^i to COO " 3 52J i w S w r 1 to r 1 w CO 88 PRACTICAL MINING W n4 PQ w w 8 $ l Sa " :: 050 ".*? sas : 8 '-' 3 i r 1 f < 8 ^J^S o8-3| &! __) a; o J^-5 .- E is I C !5 3 ~ SJJ Og-SjjjOg-jfi . to oo > co co a o S -^ H- -'s 5-1 OiCn 000 > o o bo > 05 000 gll l"Sf ? ) O O*k Oi 00 Ol ss frM i^. 00 tO CO fig? 10 COOT M ^q to CO O M C CO >*.C^ ^11 Hj O P M.O PC, td 5 C/) 90 PRACTICAL MINING MINING LAWS. The Legislature of 1897 enacted more mining laws than any previous legislative body in the State. Through the exertions of the Legislative Com- mittee of the Miner's Association, of which Tirey L. Ford is chairman, and also the good work done by Joseph H. Neff, President; Samuel Thornton, Vice President, and Julian Sountag, Secretary of the Association, backed by Assemblyman Howard of Sierra, who held the proud position of Chairman of the Assembly Committee on Mines and Mining, and who was the principal factor in obtaining favorable mining legislation, Senators Presk of Nevada, Boyce of Santa Barbara, Chapman of El Dorado, Cleaves of Shasta, Shine of Tuolumne, Smith of Kern and Voorhies of Amador counties, and Assem- blymen Caminetti of Amador, Power of Placer, Robinson of Nevada, Burnham of El Dorado and Fontana of Calaveras counties, more legislative enactments of a practical character were pushed through to the Governor, who signed them will- ingly, than at any other period in the history of the State. Among the many measures which were intro- duced and finally passed were the following: PRACTICAL ASSAYING 91 First; All legal impediments were removed from the appropriation of $250,000, which was allowed by the State for the impounding of debris, thus making available for that object $500,000, as the General Government had already appropriated a like amount pending the action of the State Legislature. Second; An act providing for the manner of locating and recording mining claims. And it is a remarkable fact that though Cali- fornia was the first State to make large and won- derful discoveries of gold, it was the last to enact laws regulating, locating and recording of miner- al claims. Every other mining State and Terri- tory passed laws to cover these important points as soon as the conditions presented themselves; but the Golden State the State replete with the history of Argonauts and mushroom millionaires the mecca of prospectors for the past quarter of a century; neglected to protect her miners by wholesome laws until this late day. The folio w- is a copy of Assembly Bill, No. 551. SECTION 1. The location of mining claims upon the public domain of the United States shall be made and perfected as provided in this Act. SEC. 2. The discoverer of any vein or lode shall immediately, upon making discovery, erect 92 PRACTICAL MINING at the point of discovery a substantial monument, or mound of rocks, and post thereon a prelimin- ary notice which shall contain: First The name of the lode or claim; Second The name of the locator or locators; Third The date of the discovery ; Fourth The number of linear feet claimed in length along the course of the vein each way from the point of discover}-; Fifth The width claimed on each side of the center of the vein; Sixth The general course of the vein or lode, as near as may be; Seventh That such notice is a first or pre- liminary notice. Such notice shall be recorded in the office of the County Recorder of the county in which the same is posted within twenty days after the posting thereof. Upon the erection of said monument and posting such notice, the discover- er shall be allowed the period of time specified in section three of this Act to enable him to perfect his location as hereinafter provided. SEC. 3. Within sixty days from the date of the discovery of the vein or lode, the discoverer must perform fifty dollars' worth of labor in de- veloping his discovery, and distinctly mark his location on the ground so that its boundaries can PRACTICAL ASSAYING 93 be readily traced, and must file in the office of the County Recorder of the county in which the claim is situated, a certificate of location, which said certificate shall state: 1. The name of the lode or claim; 2. The name of the locator or locators; 3. The date of discovery and posting of the notice, provided for in section two of this Act, which shall be considered as the date of the lo- cation . 4. A description of the claim, defining the ex- terior boundaries as they are marked upon the ground, and such additional description by re- ference to some natural objects, or permanent monument, as will identify the claim. 5. A statement that such certificate is the final or completed notice of location, and that he has performed the aforesaid fifty dollars' worth of labor in development work thereon within the aforesaid sixty day period, stating generally the nature thereof. Said certificate shall be dated and signed by or on behalf of the locator or lo- cators, and verified by them or by some one in their behalf, and when filed for record shall be deemed and considered as prima facie evidence of the facts therein recited. A copy of such certificiate of location, certified by the County Recorder, shall be admitted in evidence in all 94 PRACTICAL MINING actions or proceedings with the same effect as the original. The performance of snch labor shall be deemed a necessary act in completing snch loca- tion and a part thereof, and no part thereof shall inure to the benefit of any subsequent location. SEC. 4. The discoverer of placers or other forms of deposit, subject to location and appro- priation, under mining laws applicable to plicers, shall locate his claim in the following manner: First He must immediately post in a con- spicuous place at the point of discovery thereon a notice or certificate of location thereof contain- ing: (a) The name of the claim. (b) The name of the locator or locators. (c) The date of the discovery and posting of the notice, hereinbefore provided for, which shall be considered as the date of the location. (d) A description of the claim by reference to legal subdivisions of sections, if the location is made in conformity with the public surveys; otherwise, a description with reference to some natural object or permanent monument as will identify the claim, and vs here such claim is lo- cated by legal subdivisions of the public surveys, such location shall, notwithstanding that fact, be marked by the locator upon the ground, the same as other locations. PRACTICAL ASSAYING 95 Second Within thirty days from the date of such discovery he must record such notice or certificate of location in the office of the County Recorder of the county in which such discovery is made, and so distinctly mark his location on the ground that its boundaries can be readily traced. Third Within sixty days from the date of the discovery the discoverer shall perform labor upon such location or claim in developing thereto an amount which shall be equivalent in the aggre- gate to at least ten dollars' ($10) worth of such labor for each twenty acres, or fractional part thereof, contained in such location or claim. A failure to perform such labor within said time, shall cause all rights under such location to be forfeited and the land discovered thereby shall at once be open to location by qualified lo- cators other than the proceeding locators, but shall not in any event be open to location by such proceeding locators, and any labor per- formed by them thereon shall not inure to the benefit of any subsequent locator thereof. Fifth Such locator shall, upon the perfor- mance of such labor, file with the Recorder of the county an affidavit, showing such perfor- mance, and generally the nature and kind of work so done. 96 PRACTICAL MINING SEC. 5. The affidavit provided for in the last section, and the aforesaid placer notice or certifi- cate of location when filed for record, shall be deemed and considered as prima facie evidence of the facts therein recited. A copy of such cer- tificate, notice or affidavit, certified by the County Recorder, shall be admitted in evidence in all actions or proceedings with the same effect as the original. SEC. 6. All locations of quartz or placer for- mations of deposits, hereafter made, which do not conform to the requirements of this Act, in so far as the same are respectively applicable thereto, shall be void. SEC. 7. No record of a mining claim or mill site, made after the passage of this Act, in the records of any mining district, shall be valid. All notices of location of mining claims, mill sites, and other notices, heretofore recorded in such district records, if such notices conform to the local rules and regulations in force in such district, are hereby declared valid. Within thirty days after the passage of this Act the district recorder or custodian of the records of the several mining districts in this State, shall transmit to the County Recorders of the respec- tive counties, wherein the respective districts are situated, all the records of said respective PRACTICAL ASSAYING 97 districts, and thenceforward such County Re- corder shall be deemed and considered the legal custodian of such records. Thereafter copies of such records, certified by the County Recorder, may be received in evidence with the same effect as the originals. SEC. 8. This Act shall take effect and be in force sixty days after its passage. Third; The act of 1880, which provided a penalty of $1,000 for failure of any mining com- pany to post monthly accounts in its office, was amended so as to allow any stockholder to sue for any ACTUAL damage sustained by a neglect to post such notice. The old law worked a hardship on the small companies, located perhaps miles from any town, in mountainous districts, where it would be sometimes difficult to post such monthly statements. With the exception of the right to sue for actual damages instead of the $1,000 specified in the old statute, the law is still in force. Fourth; By a law enacted by the recent Legis- lature it requires the consent of the majority of the stock, instead of two thirds of the stock as hereto- fore, before any transfer of real estate can be made by any mining company, and a record of such con- sent must be filed in the County Recorder's office. 98 PRACTICAL MINING Fifth; Where titles are given to town site lo- cators through the Superior Judge of the district, preferance will in all cases be given to mining locators. All these are good measures, and the Miners' Association may well be proud of its work. PRACTICAL ASSAYING 99 GLOSSARY. AIR FURNACE, A fireplace at the surface for drawing out foul air from shafts or levels by its natural draught from combustion. ALUMINA, Oxidized aluminum extracted from clays, creolite, kaolin, bauxite, and what is generally known as chalk rock, or aluminite. ANGLES, DIPS and SPURS, The side extent which can be claimed upon a mineral vein is expressed by these phrases. ANHYDROUS, Waterless, as salts or minerals. ANTIMONY, A mineral, symbol Sb. Atomic weight, 129. AQUEOUS, A water solution. ARBORESCENT, A tree-like formation of minerals. ARGOL, Crude tartar. An acid salt deposited from wine. ARSENATE, Arsenic acid united with a base. ARSENIRET or ARSENIDE, Arsenic in chemical com- bination with some base, as arsenide of iron, sulphur or bismutfi. BASALT, An effusive rock composed mostly of pyrox- ene, olivine and silica. BISMUTH, A metal. Symbol Bi. Atomic weight 213. BLACKJACK, Sulphuret of zinc. BOYER, The name of a common rock drill. BREAST or BREASTING, The standing end of rock, vein or cliff of gravel immediately before taking down and blasting is called breasting. 100 PRACTICAL MINING BRECCIA, Cemented rock composed of angular frag- ments of one or more minerals which generally exhibit different colors. CALCINE, To burn off and volatize. CALCIUM, The metalic base of lime. CALC SPAR, A pure crystalized or borate of soda and carbonate of lime, sometimes combined with the matrix in vein matter. CAP ROCK, The uncertain upper rock which covers the older bedrock . CARBONATE, Carbonic acid combined with a base as carbonate of lead. CARBONATE OF SODA, Carbonic acid and oxide of so- dium chemically combined. CARBONIFEROUS, As carboniferous slate or shale, containing a little carbon, indicative of underlying coal seams. COUNTER LODE, A vein obliquely crossing the reg- ular veins of the district. CELLULAR, When a stone or mineral has many small cavities, sponge- like. CHLORIDE, Chlorine chemically united with some base, as chloride of sodium (common salt), especially found in manganese which when dissolved in muriatic acid gives off the fumes of chlorine gas. CLAY, Chiefly composed of alumina in a moist and putty-like or dry, pulverized condition, often found be- tween the vein matter and the footwall rock as gouge. CLAY COURSE, Mostly applied to a common clay seam or gouge on the side of a vein. PRACTICAL ASSAYING 101 CLEAVAGE, The planes at which cleavable stones break. COBALT, A magnetic metal, Atomic weight, 29.5. COHERENT, Firmly held together, not friable. COMPACT, When a stone is all alike, not cleavable. CONCHOIDAL, Fracturing to an irregular shaped sur- face like flint; brick or sand rock without any sign of plane or cleavage. CONGLOMORATE, A pudding stone or cementation of rocks, pebbles and sand. CUPEL, A moulded cup of bone ash for cupelling lead from the assay, leaving the gold and silver in the form of a bead. CUPRIFEROUS, Containing copper, as copper ores. DECOMPOSED, That which has undergone artificial or natural change, as the desulphurization and oxidation of the sulphurets and other metals. DENDRITIC or ARBORESCENT, Shaped or crystalized like trees. DETRITUS, Finely powdered deposits worn from hard substances. DIKE, A large zone or vein-like formation but com- posed of bed rock or country rock instead of quartz. FAULT, A cut-off or shift of a vein or seam. FERRUGINOUS, Iron, iron oxide, containing iron. FISSURE, An extensive crack or chasm in a somewhat regular plane of fracture, as a true fissure vein. FLOAT STONES, Sometimes called shoal rock, miner- alized rock lying upon the surface or near vein deposits. It sometimes directs the prospector to the vein or lode from which it came. 102 PRACTICAL MINING FLUX, Any substance that is favorable to combustion, oxidixatiou or reduction by fire. FOLIATED, Lamillar or leaf-like in form, which can be cleaved. Fox WEDGE, Wedged at two points. We find gash veins fox wedged. FRACTURE, Applied to qualify the broken surfaces of minerals, as even or uneven fracture. FRANGIBLE, Not tough, easily broken, brittle. GANGUE, Waste, all kinds of enclosing waste rock, the matrix of quartz, etc., but gangues may not all be matrixes. GLANCE, Sometimes applied to glancing or shining mineral, as copper glance, lead glance, silver glance. GLOBULAR CONCRETIONS, Minerals occurring in small, rounded forms. GOSSAN, Very rusty and finely powdered quartz. It is thought to be one of the best indications for minerals in deep sections of the vein. GOUGE, Soft clay seam between the vein matter and the walls. GRAMME, Equal to 15,433 grains Troy. GRANULAR, Minerals exhibiting small grains across the plane of the fracture. GRAPHITE, A mineral carbon. GREENSTONE, A green colored, granular stone, a kind of trap, composed of hornblende and feldspar. HORN SILVER, The common name for chloride silver because it has a horn-like surface. HORSE, A long, convex-sided portion of a foreign rock completely inclosed in the quartz or vein matter. PRACTICAL ASSAYING 103 HYDRAULIC CEMENT, A mixture of lime, magnesia, alum and silica so that it solidifies under water. INCRUSTED, When a surface is covered with some other deposit. INTERLACING, When the threads or ribbons of one mineral cross those of another. INTERSTRATIFIED, Lying between other stratifica- tions, as a layer of greenstone between other layers of slate. LAVA, Igneous rock that has been melted, forced up or thrown out from volcanoes. MATTE, The product of the first incomplete reduction of an ore, as copper matte. MICA, A thin, scale-like mineral of the true granite. OXIDE, A chemical combination of oxygen with a base. OXYGEN, A gas we extract from the air in breathing; it also forms with many acids; one-half the weight of solid 1 edrock. When united with hydrogen it is water. PALEOZOIC, Applied to the first rocks with fossil ani- mals and to the older divisions of geologic time. It in- cludes the silurian, devonian and car oniferous ages. PLATINUM, A grayish-white metal infusible by ordi- nary means, insoluble in any single acid. It dissolves in a mixture of nitric acid one part, hydrochloric acid three parts. SCHIST or SCHISTOSE, A crystaline or metamorphic rock having a slaty structure, as mica schist, argilla- ceous schist, etc. SECTILE, Minerals which are sufficiently tough to cut smootHly without crumbling. SERPENTINE, Composed of the mineral serpentine, feldspar, and pyroxene. 14 DAY USE RETURN TO DESK FROM WHICH BORROWED LOAN DEPT. This book is due on the last date stamped below, or on the date to which renewed. Renewed books are subject to immediate recall. LD LD 21A-60m-3,'65 (F2336slO)476B General Library University of California Berkeley