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 ^-"Vi i .V c 
 
 NOTES ON GRANITIC ROCKS. 
 
 By T. Stekry Hunt, LL.D., F.R.S/ 
 
 FiusT AND Second Parts. 
 
 Read before the Americau Association for the Advaucemeut of Science 
 at Troy, August 20, 1670. 
 
 CoNTKNTS OF SECTIONS.— Ji 1-2, Definitions of granite and syenite; ^ ;5 
 Structure of granitic and gneissic rocits ; $ 4-5, Felsites aud felsite-. 
 porphyries; ^ G, Gneisses and granites of New England ; §7, Granitic 
 dykes and granitic vein-stones ; % 8, Scheerer's theory of granitic 
 veins; $ 9-10. Elie dc Bennmont on granites and granitic emanations ; 
 % 11, Granitic distinguished from concretionary veins; $12, Von Cotta 
 (m granitic veins; % 111- 14. The author's views on the concretionary ori- 
 gin of granitic veins; %\v>. The banded structure of granitic veins ; $1C, 
 Granitic veins of Maine, Brunswick; $ 17, Topsham, Paris; % 18, 
 'Westl)rook,Lewistcm; crystallinelimestones; % 19, Danville, Ketchum ; 
 $ 211, Denuded granitic masses; % 21. Banded veins; Biddeford, Sher- 
 brooke ; % 22, Veins at various New England localities; % 23, Mineral 
 species of these veins ; % 24, Veins in erupted granites ; % 25, Geodes in 
 granites; § 2(5, Veins distinguished from dykes; % 27. Volgor and 
 Fournet on the origin of veins ; % 28, 29, Certain fissures and goodos 
 distinguished from veins opening to the surface; % 30, 31, Tempera- 
 tures of crystallization of granitic minerals. 
 
 § 1. The name of granite is employed to designate a supposed 
 eruptive or exotio unstratified composite rock, granular, crystal- 
 ine in texture, and consisting essentially of orthocla.se-feldspar 
 and quartz, with an admixture of mica, and frequently of a 
 triclinic feldspar, either oligoclase or albite. This is tl;e definition 
 of granite given by most writers on lithology, and applies to a 
 great portion of what arc commonly called granitic rocks ; there 
 are, however, crystalline granite-like agregatcs in which the mica 
 is replaced by a dark colored hornblende or amphibole, and to 
 such a compound rock many authors have given the name (f 
 syenite, while to those in which mica and hornblende co-exist, the 
 name of syenitic granite is applied. It is observed that in certain 
 of these hornblendic granites the quartz becomes less in amount 
 than in ordinary granites, and finally disappears altogether, giving 
 rise to a rock composed of orthoclase and hornblende only. To this 
 
 • Prom the Jmerican Journal of Science for February and March, 1871. 
 
binary nirgrcf^ato von Cotta and Zirkcl would restrict the term 
 syenite, which was already defined by d'Omalius d'llalloy to be a 
 crystalline atigre^ate of hornblcudo and feldspar, by which ortho- 
 clase-feldspar may be understood, since he describes varieties of 
 syenite, as passing into diorite ; a name by most modern lithologists 
 restricted to a compound of albite or some more basic triclinie 
 feldspar with hornblende. It is apparently by fixiling to 
 appreciate the distinction between orthoclase and triclinie feldspars, 
 in this connection, that Ilaughton has 'ately described under the 
 name of syenite rocks composed of crystalline labi'adorite and 
 hornblende, 
 
 J5 2. Naumann, regarding orthoclase and quartz as the essential 
 constituents of granite, designates those aggregates which contain 
 mica as mica-granites, and thus distinguishes them from horn- 
 blende-granites, in which the mica is replaced by hornblende. 
 Those definitions seem the more desirable as the name of granite 
 is popularly applied both to the hornblendic and the micaceous ag- 
 gregates of orthoclase and quartz. There are not wanting ex. 
 amplcs of well-defined rocks of this kind in which both mica and 
 hornblende arc almost or altogether wanting. Such rocks have 
 been designated binary granites, a term which it will be well to 
 retain. (Jhloritic and talcosc granites, into the composition of 
 which chlorite and talc enter, need only bo mentioned in this con- 
 nection. The name of syenite, so often given to hornblendic 
 granites, will, in accordance witli the views already expressed, be 
 restricted to rocks destitute of quartz. While the disappearance 
 of this mineral from hornblendic granites is held to give rise to a 
 true syenite, the same process with micaceous granites affords a 
 ((unrtzl(!ss rock consisting of orthoclase and mica, for which we 
 have no name. (Ireat ma.sses of an eruptive rock, granite-like in 
 siructure, and consisting of crystalline orthoclase or sanidin, with- 
 nut any quartz, occur in the province of (Quebec. This rock con- 
 tains in some cases a small admixture of black mica, and in others 
 an c([ually small |iro])()rtion of black liornblende. The latter 
 variety might be de.scribed as syenite, but for the former wo have 
 no distinctive name, and 1 have d(>scribed both of these by the 
 mime ol' granitoid trachytes, u term which 1 adopted the more 
 willingly on account of the peculiar composition of the leldspar ; 
 and also because compact and finely granular rocks in the same 
 region, having a similar chemical composition, present all tlie 
 characters tif ty])ical trachytes, and apparently graduate into tlie 
 
granitoid rocks just noticed.* In all attenipta to define and 
 classify compound rocks, it should be borne in mind that they are 
 not definite lithological species, but admixtures of two or more 
 mincralogical species, and can only be arbitrarily defined and 
 limited. 
 
 § 3. Having thus defined the mineral composition of granitic 
 rocks, we proceed to notice their structure. Gneiss has the same 
 mineral elements as granite, but is distinguished by the more or 
 less stratified and parallel arrangement of its constituents, and 
 lithologists are aware that in certain varieties of gneiss, this 
 structure is scarcely evident, except on a large scale, so that the 
 distinction between gneiss and granite rests rather on geognosti- 
 cal than on lithological grounds. To the lithologist, in fact, the 
 granitoid gneisses are simply more or less stratiform granites, while 
 it belongs to the geologist to consider whether this structure has 
 resulted from a sedimentary deposition, or from the flowing of a 
 semi-fluid hcteroereneous mass ^ivinsr rise to a stratiform 
 
 arrangement. 
 
 § 4, The rocks having the mincralogical composition of 
 granites present a gradual passage from the coarse structure of 
 ordinary micaceous, hornblendic, and binary granites to finely 
 granular and oven impalpable mixtures of the constituent minerals, 
 constituting the rocks known as folsite, eurite and pctrosilex. 
 These rocks are often porphyritic from the presence of crystals of 
 orthocla.se, and sometimes of crystals or grains of quartz imbedded 
 in the finely granular or impalpable paste. These felsites and 
 felsitc-porphyries are, in very many cases at least, stratified or 
 indigenous rocks, and they are sometimes found associated with 
 granular aggregates of difl'cront degrees of coarseness, which show 
 a transition from true felsites into granitic gneisses. The resem- 
 blances in ultimate composition between felsites, granites and 
 granitic gneisses are so close that it cannot be doubted that their 
 difterenccs are only structural. 
 
 § 5. Felsites and felsitc-porphyries arc well known in eastern 
 Massachusetts, at Lynn, Saugus, Marblehead and Newburyport, 
 and may be traced from Machias and Eastport in Maine, along 
 the southern coast of New Brunswick to the head of the Bay of 
 Fundy, with great uniformity of type, though in every place subject 
 
 *^raor. .Touvnal of Science, II, xxxviii, 0.'). Soc also Z'wkv], Pctro- 
 tjraphic, ii, ni>. 
 
tu considerable variatious, from a compact jasper-Iikc rock to more 
 or less coarsely granular varieties, all of which arc often porphy- 
 ritic from feldspar crystals, and sometimes include grains or 
 crystals of quartz. The colors of these rocks are generally some 
 shade of red, varying from flesh-red to purple ; pale yellow, gray, 
 greenish and even black varities are however occasionally met wi^h. 
 These rocks are throughout this region distinctly stratified, and 
 are closely associated with dioritic. chloritic and epidotic strata. 
 They apparently belong, like these, to the great Huronian system. 
 
 § G. Many of the so-called granites of Nt\\ England are true 
 gneisse:?, as for example, those quarried in Augusta, Ilallowell, 
 Brunswick, and many other places in Maine, which are indigen- 
 ous rocks interstratified with the micaceous and hornblendic 
 schists of the great AVhitc Mountain series. To this class also, 
 judging from lithological characters, belong the so-called granites 
 of Concord and Fitzvvilliam, New Hampshire. These indigen- 
 ous rocks are tenderer, less coherent, and generally finer grained 
 than the eruptive granites, of which wc have examples in the 
 micaceous granite of Biddcford, iMainc, and the hornblcudic 
 granites of Marblehcad andStonchani, Mass., and Newport, Ehode 
 Island, in all of which localities the contact of the eruptive mass 
 with the enclosiiig rock is plainly seen, as is also the case farther 
 eastward, on the St. Croix and St. John's Rivers, in New Bruns- 
 wick, and in the Cobcquid Tlills and elsewhere in Nova Scotia. 
 The hornblendic granites of Gloucester, Salem and Quiucy, 
 Massachusetts, seem also, from their litholoijrical characters, to 
 belong to the class of exotic or true eruptive granites. 'i^ The 
 farther discussion of the nature and origin of these gneisses and 
 granites is reserved for another occasion, and wc now proceed to 
 notice the history of granitic veins. 
 
 § 7. The eruptive granitic masses just noticed, not only include 
 fragments of the adjacent rocks, especially near the line of contact, 
 but very often send off dykes or veins into the surrounding strata. 
 The relation of these with the parent mass is however generally 
 obvious, ami it niay be seen that they do not differ from it except 
 in being often finer grained. These injected or intruded veins 
 are not to be confounded with a third class of granitic aggregates, 
 \vhi(;h 1 have elsewhere described as granitic veinstones, or, to 
 
 * T. 8. Hunt on the Geology of EaHteru Now England, Amor. Journal 
 of Seienco for .liily 1H7(>, p. 88; also Notes on the (ieolog}' of tlie 
 vicinity of Boston. Proc. lloston Nut. Hist. Sop., Oct. ID, 187(». 
 
express their supposed mode of formation, endogenous granites. 
 They are to the gneisses and mica-schists, in which they are 
 generally enclosed, what calcite veins arc to stratified limestonr-. 
 and although long known, and objects of interest from their mineral 
 contents, have generally been confounded with intrusive granites. 
 § 8. Scheerer, in his famous essay on granitic rocks, which 
 appeared in the Bulletin of the Geological Society of France in 
 1847, (vol. iv, p. 468), conceives the congealing granitic rocks 
 to have been impregnated with '"'a juice" which was nothing else 
 than a highly heated aqueous solution of certain mineral matters. 
 This, under great pressure, oozed out, penetrating even the 
 stratified rocks in contact with the granite, filling cavities and 
 fissures in the latter, and depositing therein crystals of quartz and 
 of hornblende, the arrangement of which shows them to have been 
 of successive growth. Neither Scheerer nor Virlct d'Aout, who 
 supported his views, however (ibid., iv. p. 49o) extended them to 
 feldspathic veins, though Daubree, at an earlier date, had described 
 certain granitic reins in Scandinavia as having been formed by 
 secretion, rather than by igneous injection as maintained by 
 Durocher. 
 
 ^ 9. Elie de Beaumont, starting from the hypothesis of a 
 cooling liquid globe, imagined " a bath of molten matter on the 
 surface of which the first granites crystallized." From the ruins 
 of these were formed the first sedimentary deposits, but directly 
 beneath were other granitic masses, which became lixcd immedia- 
 tely afterward. "Some parts of these masses, coagulated from 
 the commencement of the cooling process, but not completely 
 solidified, were tlien erupted througli the sedimentary deposits" 
 just mentioned. '' In these jets of pasty matter" were contained 
 many of the rarer elements of the granitic magma, which were 
 thus concentrated in the outermost jiortions of the granitic crust, 
 and in the ramifications formed by these portions in the masses 
 through which they were forced by the eruptive agents. Those 
 portions of the granitic masses and their ramifications in which 
 these rarer elements are concentrated, are distinguished from the 
 rest of the masses alike by their exterior position and their pecu- 
 liar structure. They are often coarse-grained, and include the 
 pegmatites, tourmaline-granites, and veins carrying cassiterite and 
 columbito often abounding in <(Uialz. These mineral products 
 arc to be regarded as emanations from the granite, and are de- 
 gcribed as a gninitic aura, constituting what Humboldt has call- 
 
6 
 
 ed the penumbra of the granite. (Bitll. Soc. Geol. de Fraiice, (2) 
 iv, 1249. See particularly pages 1295, 1321 and 1323). 
 
 § 10. While Fournet, Durocher and Riviere eonceived the 
 granitic magma to have been purely anhydrous, and in a state of 
 simple igneous fusibn, Elie de Beaumont maintained with Poulett- 
 Scropc and Schcerer that water bad in all cases intervened, and 
 that a few hundredths of water might, at a lov/ red heat, have 
 given rise to the condition of imperfect liquidity which he imagin- 
 ed for the material of the injected granites. The coarsely crystal- 
 line granitic veins were, according to him, veins of injection, and 
 he speaks of them as examples in which " the phenomena essential 
 to the formation of granite had been manifested with the great- 
 est intensity." The granitic emanations, which are supposed to 
 have furnished the material of these veins, appear to be regarded 
 by him as the result of a process of eliquation from the congealing 
 oranitic mass. Do Beaumont is careful to distinguish between 
 them and those emanations which are dissolved in mineral waters, 
 or are exhaled as volcanic vapors (page 1324). To the agency of 
 such waters he ascribes the formation of concretionary veins, which 
 are generally characterized by their symmetrically banded struc- 
 ture. He further adds that granites, as to their mode of forma- 
 tion, offer a character intermediate between ordinary veins and 
 volcanic and basic rocks. This is conceivable as regards granitic 
 veins, since these, according to him, although formed by injec, 
 tion, and not by concretion, result from a process of emanation 
 from the parent granitic mass, which may bo described as a kind 
 of segregation. 
 
 I have thus endeavored to give, for the most part in his own 
 words, the views on the origin of granites enunciated by the great 
 French geologist in his classic essay on Volcanic and Metalliferous 
 Emanations, published in 1847. They belong to the history of 
 our subject, and are remarkable as a clear and complete expression 
 of those modified plutonic views which are probably held by a 
 great number of enlightened geologists at the present time. My 
 reason for dissenting from them, and the theories which I offer in 
 their ptcad will be shown in the sequel. 
 
 § 11. Elie de Beaumont, while regarding the formation of 
 granitic veins as a process in which water intervened to give 
 fluidity to the magma, was careful to distinguish the process from 
 that of the production of concretionary veins from aqueous solution, 
 and supposed the fissures to have been filled by the injection of a 
 
jet of pasty matter derived from a consolidating granitic mass, 
 Daubrdo and Scheerer, in describing the granitic veins of Scandina- 
 via, conceive tlio material filling them to have been derived from 
 the enclosing crystalline strata instead of an unstratified granitic 
 nucleus, but do not, so far as I am aware, compare their Ibrmatit 
 to that of concretionary veins. Their publications on this subject, 
 it should be said, arc both anterior to the essay of de Beaumont. 
 
 J^ 12. The notion that all granitic veins are the result of some 
 process of injection, and not to be confounded with concretionary 
 veins, seems indeed to have been general up to the present time. 
 Even von Cotta, while strongly maintaining the aqueous and 
 concretionary origin of metalliferous veins in general, when 
 describing thosu consisting of quartz, mica, feldspar, tourmaline, 
 garnet, and apatite, with cassiterite, wolfram, etc., which occur at 
 Zinnwald and at Johanngeorgcnstadt, is at a loss whether to regard 
 these veins, from their granitic character, as ignc<ms-fluid 
 injections or as concretionary lodes. In support of the latter view 
 lie refers to their more or less regular and symmetrically banded 
 structure, and while recalling the fact that mica and feldspar may 
 both be formed in the humid way, considers the nature of these 
 veins to be very problematical, and tlie question of their origin a 
 difficult one. — {Ore J)rpi)sifs, Prime's translation, 1870, pages 
 no— 12i). 
 
 i§ 13. I have for several years taught that granitic veins of the 
 kind just referred to are concretionary and of aqueous origin. 
 In 1863 I described certain veins in the crystalline schists of the 
 Appalachian region of Canada, ''where flesh-redorthocla.se occurs 
 so intermingled with chloriti; and white quart/ as to show the 
 contemporaneous formation of the three species. The orthoclase 
 generally predominates, often reposing upon or surrounded by 
 chlorite; at other times it is imbedded in quartz, which covers 
 the latter. Drusy cavities are also lined with small crystals of 
 the feldspar, and have been subsequently filled with cleavable 
 bitter-spar, sometimes associated with specular iron, rutile and 
 sulphuretted copper ores." A study of these veins shows a tran- 
 sition from those " containing quartz and bitter-spar with a little 
 chlorite or talc, through others in which feldspar gradually pre- 
 dominates, until we arrive at vchis made up of orthoclase and 
 quartz, sometimes including mica, and having the character nf a 
 coarse granite; the occasional presence of sulphunls ol' copper 
 and specular iron characterizing all of them alike It is probalik- 
 
8 
 
 that these, and indeed a great proportion of quartzo-feldspathic 
 veins are of aqueous origin, and have been deposited from solu- 
 tions in fissures of the strata, precisely like metalliferous lodes. 
 This remark applies especially to those giMnitic veins which in- 
 clude minerals containing the rarer elements. Among these are 
 boron, phosphorus, fluorine, lithium, rubidium, glucinum, zirco- 
 nium, caesium, tin and columbium ; which characterize the mineral 
 species apatite, tourmaline, lepidolite, spodumene, beryl, zircon, 
 allanite, cassiterite, colurabite, and many thers." — {Geology of 
 Canada, p. 476, also p. 644.) 
 
 In this connection I referred to the occurrence of orthoclase with 
 quartz, calcite, zeolites, epidote and native copper in certain 
 mineral veins of Lake Superior, so well described by Prof. J. D. 
 Whitney. (American Journal of Science, II, xxviii, 10). The 
 associations, according to him, show the contemporaneous crystal- 
 lization of the copper, natrolite, calcite and feldspar, which hist 
 was found by analysis to be a pure potash-orthoclase. 
 
 § 14. In 1864, this view was still farther insisted upon in the 
 Amer. Journal of Science (II, xxxvii, 252), where, in speaking 
 of mineral veinstones " which doubtless have been deposited 
 from aqueous solution," it is added, "while their peculiar arrange, 
 ment, with the predominance of quartz and non-silicated species, 
 generally serves to distinguish the contents of these veins from 
 those of injected plutonio rocks, there are not wanting cases in 
 which the predominance of feldspar and mica gives rise to aggre- 
 gates which have a certain resemblance to dykes of intrusive gran- 
 ite. From these, however, true veins are generally distinguished 
 by the presence of minerals containing boron, fluorine, phosphorus, 
 ca3sium, rubidium, lithium, glucinum, zirconium, tin, columbium, 
 etc. ; elements which are rare, or found only in minute quantities 
 in the great mass of sediments, but are here accumulated by de- 
 position from waters, which have removed these elements from 
 the sedimentary rocks and deposited them subsequently in fissures." 
 
 In the Report of the Geological Survey of Canada for 1S65 (p. 
 192), I have, in describing the veins of the Laurentian rocks, in- 
 sisted still farther on the distinction just drawn between granitic 
 dykes and granitic veinstones, which latter I have proposed to 
 call endogenous rocks, to indicate the mode of their formation, 
 and to distinguish them from intrusive or exotic rocks, and sedi- 
 mentary or indigenous rocks. 
 
 § 15. The peculiar banded arrangement, which is so charac- 
 
9 
 
 
 teristic ia concretionary veins not granitic in composition, is pro- 
 bably not less marked in granitic veinstones, and often appears in 
 these in a remarkable manner, showing that they have been form- 
 ed by successive depositions of mineral matter, and generally in 
 open fissures. This structure, and various peculiarities to be ob- 
 served in granitic veinstones, will be best illustrated by descrip- 
 tions of various localities, most of which I have personally examin- 
 ed. It is proposed to notice first, the veins of the gneiss and mica- 
 schist series of New England, and secondly those of the Laurcn- 
 tian rocks of New York and Canada. In the latter class will bo 
 noticed the more or less calcareous veinstones into which the 
 Laurentian granitic veins are found to graduate. 
 
 § 16. It is in the series of micaceous schists with interstratified 
 gneisses (§ 6) which I have elsewhere provisionally designated 
 the Terranovan series,^- that I have seen concretionary granitic 
 veins in the greatest abundance and on the grandest scale. This 
 stratified system, which is well seen in the White Mountains, 
 appears to extend southward to Long Island Sound and north- 
 eastward beyond the limits of Maine. It is in this state that I 
 have particularly studied the granitic veinstones of this system 
 whose history may be illustrated by a few examples from notes 
 taken on the spot. In Brunswick the strata near the town are 
 fine-grained, friable, dark colored, micaceous and horiiblendic, 
 passing into mica-schist on the one hand, and into well-marked 
 gneiss on the other, and dipping to the S. E. at angles of from 
 15° to 40°. Very similar beds are found in the adjoining town 
 of Topsham, and in both places they include numerous endogenous 
 granitic veins. The course of these is generally N. W., or at right 
 angles to the strike, though occasionally for short distances with 
 the strike, and intercalated between the beds ; the veins vary in 
 breadth from a few inches to sixty feet, and even more. They 
 generally consist in great part of orthoclase and quartz, with some 
 mica and tourmaline, and offer in the associations and grouping 
 of these minerals many peculiarities, which arc met with not only 
 in different veins but in different parts of the same vein. In 
 
 * Amer. Journalof Science for July, 1870, page 83, and Can. Natm'alist, 
 Y. p. 198. — The rocks of this Whitc-Mouutaiii Ferics aro in the present 
 state of onr knowledge supposed to be newer than the llurouian system 
 noticed in $ 5, to which, with Macfarlauo and Credner, I refer the crystal- 
 line schists, with associated serpentines and diorites, of the tireen 
 Mountains. 
 
10 
 
 some cases, colorless vitreous quartz predominates greatly, and en- 
 closes crystals of milk-white orthoclase, often modified, and from 
 one to several inches in diameter. At other times pure vitreous 
 quartz forms one or both walls, or the center of the vein, or else is 
 arranged in bauds parallel with the sides of the vein, and some- 
 times a foot or more in thickness, alternating with similar bands 
 consisting wholly or in great part of orthoclase, or of an admixture 
 of this minera' with quartz, having the peculiar structiv.o of what 
 is called graphic granite, or else presenting a fi-jcly granitoid 
 iuixture of the two minerals, with little or no mica, and with small 
 crystals of deep red garnet. Prisms of black tourmaline are also 
 met with iu those veins, and more rarely beryl and even chryso- 
 bcryl. In the rock-cutting on the Lewistcn railroad, just below 
 Topsham bridge over the Androscoggin, there is a fine exhibition 
 of these veins, which present alternate coarser and finer grained 
 layers, traversed by lon.g spear-shaped crystals of dark mica pasa- 
 iiig from one layer to another. 
 
 ^5 17. A remarkable example of a vein of considerable dimen- 
 sions is seen in the feldspar-quarry in Topsham, which occurs in a 
 dark fine-grained friable micaceous schist. At the time of my 
 visit, in 1860, the limits of the vein were not seen, though largo 
 quantities of white orthoclase and of vitreous quartz had already 
 been extracted. Those were each nearly pure, and in alternate 
 bands, the quartz presenting drusy cavities lined with remarkable 
 tabular crystals. One band was made up in great part of largo 
 crystals of mica, and portions of the vein consisted of a granular 
 saccharoidal feldspar. The famous locality of red, green and blue 
 tourmalines, with beryl, lepidolite, amblygonito, cassitorite, etc., 
 at Mount Mica in Paris, is a huge granitic vein, which, with many 
 others, is included in a dark colored very micaceous gneiss. 
 
 § 18. In Westbrook numerous small veins of this kind, holding 
 coarsely lamellar orthoclaso with black tourmaline and red garnet, 
 intersect strata of fine-grained wliitish granitoid gneiss. In Wind- 
 ham the dark colored staurolitc-boaring mica-sohist of this scries 
 is traversed by a granitic vein liolding crystals of beryl. In 
 Lewiston alaigo vein of coarse graphic granite, holding black 
 tourmaline, and showing fine-grained bands, cuts a great mass of 
 bluish gneissoid limestone, which forms an escarpment near the 
 railroad, almut half a mile boljw the town. This limestone, wliich 
 clips eastward about If)"^, is interlaminatcd with thin quartzito 
 beds, which arc .<5ccn on weathered surfaces to be much contorted. 
 
 
11 
 
 The bluish crystalline limestone is mixed with grains of greenish 
 pyroxene, and includes nodulav granitic masses of white crystalline 
 orthoclise with quartz, enclosir"^ large plates of graphite, crystals 
 of hornblende, and more rarely of apatite. These associations of 
 minerals are met with in the granitic veins of the Laurentian 
 limestones, to be noticed elsewhere. The limestone of Lewiston, 
 however, appears to be included in the great mica-schist series of 
 the region ; where similar beds, though legs in extent, are met with 
 in various places, sometimes associated with pyroxene, garnet, 
 idocrase and sphene. A thin band of impure pyroxcnic limestone, 
 like that of Lewiston, occurs with the mica-schists ou the Maine 
 Central Railroad, near Danville Junction, and beds of a purer 
 crystalline limestone were formerly quai-ricd in the south-east part 
 of Brunswick, where they are interstratified with thin-bedded dark 
 hornblcndic and micaceous gneiss, dipping S. E. at a high angle. 
 
 § 19. At Danville Junction strata of hornblcndic and mica- 
 ceous gneiss, passing into mica-schists, dip S. E, at moderate 
 angles, and include huge veins of endogenous granite. Two of 
 these appear in the hill just south of the railroad station, appar- 
 ently running with the strike of the beds. They are seen to rest 
 upon the mica-schist, and in one of them a mass of this rock, three 
 feet in width, is enclosed like a tongue in the granite, which has a 
 transverse breadth of about seventy-five feet. Notwithstanding 
 the apparent intercalation of these granitic masses the proof of 
 their foreign origin is evident in a transverse fracture and slight 
 vertical dislocation of the mica-schist, around the broken edges of 
 which the granite is seen to wrap. The endogenous character of 
 this granite is well shown by its banded structure ; bolts of white 
 quartz some inches wide alternate with others of coarsely clcavable 
 orthoclase, while other portions hold black tourmalines and garnets 
 of considerable size. 
 
 The evidence of disturbance of the strata in connection with 
 these endogenous granites is seen on a large scale at the falls of the 
 Sunday River in Ketchum. There, mica-schists and gneisses, 
 similar to those already noticed, enclose great masses of endoge- 
 nous granite, which are seen to bo transverse to the strata. On 
 one side of such a mass more than sixty feet wide, the schistose 
 strata are twisted from their regular N. E. strike to the N. W., 
 and so enclosed in the granite as to appear as if interstratified 
 with it for short distances. The banded structure of the trans- 
 verse granite veina is here very marked. 8omc portions present 
 
12 
 
 cleavage-planes of orthoclase six inches iu diameter ; other parts, 
 which are less coarse, abound in mica. Similar banded granite 
 veins abound in the adjoining towns of Newry and North Bethel, 
 and sometiaoes present layers of quartz bix inches or more in thick- 
 ness, besides large crystals of mica, and more rarely apatite. These 
 veins are often irregular in shape and bulging at intervals, and 
 they sometimes run partially across the beds, which seem to have 
 been distended and disturbed, a fact which was also observed in the 
 thin-bedded schists in contact with some of the veins in Brunswick, 
 and is apparently due to the expansive force of crystallization, as 
 noticed in § 27. 
 
 § 20. The locality already described at Danville oifers an 
 instructive example of a phenomenon often met with in the region 
 now under consideration, where granitic masses, resisting the 
 actions which have degraded the soft enclosing schists, stand out 
 in relief on the surftice, and seem to constitute the rock of the 
 country. A careful search will however show that they are 
 simply veins or endogenous masses of very limited dimensions, 
 rising from out of the micu-schists, which are often concealed by 
 the soil. This is well seen about the lower falls of the Presump- 
 scott near Portland, where the micu-schists with gome line-grained 
 gneisses, dipping S. E. at angles of from 30'^ to 40^^, enclose large 
 numbers of granitic veins, which, though sometimes but a few 
 inches in breadth, often measure twenty or even fifty feet, and are 
 usually very coarse-grained, with white mica, black tourmaline, 
 and more rarely beryl. They are sometimes transverse to the 
 stratification, but more often parallel, and, rising above the soil, 
 are very conspicuous. 
 
 § 21. We have already noticed the exotic granites of Bidde- 
 ford, which are intruded among fine-grained bluish or grayish 
 silicious strata. These latter are traversed by numerous veins of 
 endogenous granite, which are very unlike in aspect to the intru- 
 sive rock. One of these veins near Saco Pool, has a diameter of 
 about an inch and a half, and presents on either wall a layer of 
 yellowish crystalline feldspar about one fourth of an inch in tiiick- 
 ness, which includes long plates of dark brown mica. These 
 penetrate the central portion of the vein, which is a broadly crys- 
 talline bluish orthoclase, enclosing snuill portions ol' quartz after 
 the manner of a graphic granite. The yellowish and less coarsely 
 crystalline feldspar with its accon)nanying mica, had evidently 
 lined the walls of the vein while the ecutro yet remained open, and 
 
13 
 
 had moreover entirely filled a small lateral branch. The same 
 conditions are seen in the filling of other veins in this vicinity, 
 which are often much larger, and present upon their walls bands 
 of an inch or two of the yellowish feldspar with mica. 
 
 The successive filling of a granitic vein is still more clearly 
 shown in a specimen from Sherbrooke, Nova Scotia, which I owe 
 to the kindness of Prof. H. Y. Hind. The vein, which is seen to 
 be transverse to the adherent fine-grained mica-schist, has a 
 breadth of neai'ly four inches, about two- thirds of which is sym- 
 metrical, and is included between two layers, perpendicular to 
 the walls, consisting of a fine-grained mixture of white feldspar 
 and quartz, each about one-fourth of an inch thick, and marked 
 by subordinate zones, more or less quartzose. Within these 
 two bands is a coarser aggregate, consisting of two feldspars, with 
 some quartz and muscovite, plates of which, and crystals of pink 
 orthoclase penetrate an irregular layer of smoky quartz varying 
 from one-eighth to one-half an inch in diameter. This fills the 
 center of the symmetrical portion of the vein, on one side of which 
 is the mica-schist, while the other is bounded by a band of more 
 than half an inch of fine-grained granite with yellowish-green mica, 
 presenting large crystals of feldspar near the outer margin, where 
 it is succeeded by a layer of pure smoky vitreous quartz of about 
 the same thickness, whose outer surface, against the wall, shows 
 irregular bosses or nodular masses, the depressions between which 
 are occupied by a finely granular micaceous aggregate unlike any 
 other part of the vein in texture. This description may be read 
 in connection with the remarks in § 27. 
 
 Dana has described and figured a similar granitic vein, band- 
 ed with quartz, observed by him at Valparaiso in Chili, (Manual 
 of Geology, 18G2, p. 713), ='= and has moreover maintained that 
 such granitic veins, like ordinary mctalliforous lodes, are clearly 
 concretionary in their origin, and have been filled by slow and suc- 
 cessive deposits from aqueous solutions. His testimony to the 
 views which I have advocated in this pnper had been overlooked 
 by me, or it would have been noticed in 4^ 12. 
 
 ^ 22. The numerous granitic veins so well known to mineral- 
 ogists in the nilca-schists and gneisses of New Ilainpshire, Mas- 
 sachusetts and Connecticut, including among other familiar 
 localities, (Jrafton, Acworth, Royalston, Norwich, Goshen, dies- 
 
 * Prom U. S. Exploring Expeclilion. Rcporton Ibc Cicology, 1843, p. 570, 
 
14 
 
 terfield, Middlctown and Iladdani, seem from descriptions, and 
 from tlifir mineral constituents to be similar to those of Maine, 
 already montioned. With the exception of Royalston however 
 these localities are as yet only known to me from specimens and 
 descriptions. It i.:i noteworthy that at this last the finely-crystal- 
 lized beryls arc directly imbedded in vitreous quartz, and the 
 same is the case with the blue and green tourmalines of Goshen. 
 A remarkable example of a vein of this character occurs in Buck- 
 field, Maine, described to me by Prof. Brush, where large isola- 
 ted crystals of white ortlioclase, nearly colorless muscovite and 
 brown tourmaline occur in a vein of vitreous quartz. At Paris 
 and at Hebron, Maine, tourmalines are found penetrating crystals 
 of quartz. The flattened tourmalines and garnets found in mus- 
 covite at several localities in New England, are well known to col- 
 lectors, and a curious example of enclosure has been observed by 
 Prof. Brush at Hebron, where crystals of muscovite are encased 
 in lupidolite. 
 
 § 23. The following list includes the principal mineral species 
 found in these granitic veins in New England ; apatite, ambly- 
 gonite, triphyllinc, autunite, yttroeerite, orthoclase, albite, oligo- 
 clase, spodumono, iolite, muscovite, biotitc, lepidolite, cookeite, 
 chlorite, chloropliyllite, garnet, cpidote, tourmaline, beryl, zircon, 
 quartz, chry.'jo beryl, automolite, cassitoritc, rutile, brookite, uran- 
 initc, columbito, pyrochlorc, scheelite, and blsmutite. As I am 
 not aware that chlorite has hitherto been mentioned as a constitu- 
 ent of these veins, it may be said that it occurs in one at Albany, 
 Maine. To the above should probably be added the rare species 
 nepheline, cuncrinite and sodalite, which have long been known in 
 boulders of a granite-like rock in Maine. According to informa- 
 tion given me by Prof. Brush, green clocolite with white ortho- 
 clase and black biotitc occurs in a granitic vein twenty feet in 
 breadth, lately observed in the northwest part of Litchfield, 
 Maine. 
 
 § 2-4. We liavc seen that these endogenous veins are found 
 alike in the gneisses, niica-sohists, limestones and quartzose strata 
 of this region. They are also met with in tlie eruptive granites, 
 small fissures in which are sometimes filled with coarsely crystal- 
 line orthoclase, smoky quartz, various micas and zircon. Examples 
 of this arc seen in the granites of Ilampstcad, New Brunswick, 
 and JNIt. Uniacke, Nova 8cotia. The fine green feldspar of Cape 
 Ann, Mass., and the micas, oryophyllite and lopidomehmc with 
 
15 
 
 zircon, dcsci'ibed by Prof, Cooke, from the same region, occur ht 
 veins in the hornblendic f^ranites of that locality. Small vcin.s 
 cutting a somewhat similar rock at Marblchcad, contain crystal- 
 lized green epidotc with white ((uartz and red orthoclase. 
 
 § 25. The veins which we have described are frequently of 
 very limited extent, and seem to occupy short and irregular fis- 
 sures, while in other cases the mineral aggregates which charac- 
 terize them occur in nes*:s or geodcs. This is seen near Fall 
 Brook in the Nerepis valley in New Brunswick, where the red 
 micaceous granite is in one part very friable, and presents irregu- 
 lar geode-like cavities, sometimes several inches in diameter, 
 which are partially filled by radiating prisms of black tourmaline, 
 accompanied with quartz and albite crystals, and more rarely 
 small octahedrons of purple fluoritic. The enclosing granite in 
 composed of deep red orthoclase, with small portions of a white 
 triclinic feldspar, smoky quartz and black mica. The conditions 
 seen at this place recall the description of the famous locality of 
 feldspars, etc., at Fariolo near Bavcno in Northern Italy. The 
 rock, described as a granite, resembles, in a specimen before me 
 some of the intrusive granites of New Brunswick, and contains a 
 pink and a while feldspar, with a little Hack mica. It includes 
 veins of graphic granite, and also spheroidal masses, which differ 
 in texture fro:;i the mass of the rock, and present geodes of con- 
 siderable size, lined with fine large red and white crystals of or- 
 thoclase, accompanied by albite, epidote, quartz, fluorine and a 
 greenish mica (or chlorite) all of which, according to Fournet, 
 are so mingled and interlocked as to show that they are of contem- 
 poraneous origin. To these arc to be added, as occurring in the 
 geodcs, prehnite, calcite, liyalite, and specular iron. The ortho- 
 clase crystals often have adhering to their opposite faces crystal- 
 line plates of albite, which are larger than the planes to 
 which they are attached. The crystals of orthoclase moreover 
 IVcquently present hollowod-out or hopper-shaped faces, which 
 Fournet happily describes as resulting from the forming of the 
 frame-work or skeleton of the crystals, when the material was not 
 sufficient for their completion. A process analogous to this is 
 often seen in crystallization, whether I'roni fusion, solution or 
 vaporous condensation, giving rise in some cases to external de- 
 pressions, and in others to internal cavities in the resulting crystals. 
 Fournet ascribes the formation of the geodes in the granito of 
 Fariolo to a process of shrinking, and a subsequent sogregalioa 
 
16 
 
 filling the resulting cavities, in •which he is forced to recognize 
 the intervention of water, though by no means admitting the 
 aqueous origin of veins, since he holds even those of quartz to 
 have been formed by igneous injection. (^Geologic Lyonnaise, 
 *278. 
 
 § 26. When we consider the cause which has produced the fis- 
 sures in the mica-schists and gneisses of New England, which 
 hold the granitic veins already described, it is to be remarked 
 that their comparative abundance, their shortness aud their ir- 
 regularity distinguish tlicm from the fissures which are filled with 
 eruptive rocks. Examples of the latter may be seen near Dan- 
 ville, Maine, where djkes of fine-grained dolerite are posterior to 
 the endogenous granitic veins here occuring in the mica-schist. 
 These dykes may be supposed to be dependent upon movements 
 in the earth's crust opening deep fissures which connected with 
 some softened rock far below. Through such openings were ex- 
 travasated the exotic rocks, whether granites or dolerite?, — more 
 or less homogeneous mixtures, often widely different in composition 
 from the encasing rocks. The endogenous veins, on the contrary, 
 are distinguished not only by their more or less heterogeneous and 
 often banded structure, but by the fact that their principal con- 
 stituents are the mineral species most common in the adjacent 
 strata. 
 
 § 27. Volgcr has attributed the formation of the openings 
 containing concretionary veins to the force of crystUlization, which 
 is shown to be very great in the congelation of water and the 
 crystallizing of salts in cavities aud fissures. Such a process once 
 commenced in an opening in a rock would, he conceived, be sufScient 
 to make still wider the fissure, which might be fed by fresh solutions 
 passing by capillarity through the pores of the rock. If this 
 process were to become concentrated around several points, the 
 intermediate space might be so opened that free crystallization 
 could go on, resulting in the production of geodes in veins thus 
 formed. 
 
 Fournet, on the other hand, suggests that contraction in the 
 cooling of erupted granites gave origin to the fissures and geodes 
 now filled or partially filled with crystalline minerals at Fariolo, 
 and we may readily suppose that a process of contraction attendant 
 upon the crystalline aggregation of the materials of sedimentary 
 strata, would give rise to rifts or fissures therein. The lesions 
 thus produced in the solid rocks become more or less completely 
 
repaired, if we may so speak, by an eflfusion ol' mineral matter 
 from the walls, and thus are generated geodes, irregular masses, 
 and many veins. That the process imagined by Volger may in 
 some cases intervene, and may act subsequently to the one just 
 imagined, is highly probable, though we are disposed to assign it 
 but a secondary place in the production of vein-fisures. It oflFers 
 however the most plausible explanation of the distortion of the 
 thin-bedded strata already noticed in connection with some of the 
 concretionary granitic veins of Maine, which seem, by a process of 
 growth, to have bent outward the adjacent beds. The vertical 
 transverse veins are, in many cases at least, unsymmetrical, as if 
 they had grown from one side, while the distortion of the beds) 
 sometimes attended by irregular concretions in the banded vein- 
 stone, appears at the opposite wall. The notion that the vein- 
 fissures opened as crystallization advanced, has been defended by 
 Griiner. 
 
 § 28. It is not here the place to discuss how far the greater 
 and deeper fissures of the earth are dependent upon the contraction 
 of sediments, as just explained, or upon the wider spread move- 
 ments of the earth's crust, though even of these it may be said that 
 they are more or less directly the results of a process of contraction. 
 It should however be noted that while some fissures of this kind 
 are filled with dykes of erupted rocks (§2G), others hold concre- 
 tionary veins, which are to be distingnished f;om the class of 
 veins just described, inasmuch as the openings in which they were 
 deposited evidently communicated with the surface of the earth. 
 Examples of these are seen in the lead and zinc-bearing veins with 
 calcite amd barytine, which traverse vertically the carboniferous 
 limestone in England, and enclose in their central portions material 
 of liassic age, abounding in the remains of a marine and a fresh- 
 water fauna, which show these veins to have been deposited in 
 fissures communicating with the surface-waters of the liassic period. 
 For a description of these veins by Mr. Charles Moore, see the 
 Report of the British Association, for 1869, and Amer. Jour, of 
 Science, IT, 1, 305. Similar evidence is afibrded by the existence 
 of rounded pebbles imbedded in veins, as observed in Bohemia, 
 and also in Cornwall, where numerous pebbles both of slate and 
 quartz were found at a depth of six hundred feet in a lode, cemented 
 by tinstone and sulphuret of copper. (Lyell, Student's Elements 
 of (jeology, p. 593. Not less instructive in this connection are 
 the observations of Mr. J. A. I'liillips, on the silicious vciiistones 
 
18 
 
 now ia process of formation in open fissures in Nevada (L, E. and 
 D. Phil. Mag. (4), xxxvi, 321, 422, Anier. Jour, of Science, II, 
 xlvii, 138). \Vc cannot doubt that the ancient, like these modern 
 veins, have been channels for the discharge of subterranean mineral 
 waters, and it would seem that while the deposition of theincrust- 
 ing materials on the walls of the fissure is in part due to cooling, 
 and in part perhaps to the infiltration, in some cases, of precipitants 
 from lateral sources, it is chiefly to be ascribed to the reduction of 
 solvent power consequent upon the diminution of pressure as the 
 waters rise nearer to the surface. This conclusion, dcduciblc from 
 the researclies of Sorby on the relation of pressure to solubility, I 
 have pointed out in the Geological Magazine for February, 1868, 
 p. 57, Sec also Amcr. Jour, of Science, II, 1, 27. 
 
 § 29. There is evidently a distinction to bo drawn between 
 veins which have been open channels, and the segregated masses 
 and gcodes formed in cavities which appear to have been every- 
 where limited by the enclosing rock. In the former case, a free 
 circulation of the mineral solution would prevail, while in the latter 
 there could be no renewal of it except by percolation or difi'usion 
 through the rock. A comparison between the contents of gcodes 
 and fissure-veins, whether in granite rocks or in fossiliferous lime- 
 stones, will however show that these differences do not sensibly 
 affect the mineral constitution of the deposits. 
 
 § 30. The range of conditions under which the same mineral 
 species may be formed is apparently very great. Sorby, from his 
 investigations of the fluid-cavities of crystals, concludes that the 
 quartz which occurs with cassiterite, mica and feldspar in the 
 granitic veins of Cornwall, must have crystallized at temperatures 
 from 200^* to 340'-' Centigrade, and under great pressure, con- 
 ditions which we can hardly suppose to have presided over the 
 production of the crystallized quartz found in the unaltered 
 tertiarics of the Paris basin, or the auriferous conglomerates ol' 
 California. In like manner beryl, though a common mineral of 
 the tin-bearing granite veins, like tliose studied by Sorby, occurs 
 at the famous emerald mine of Muso in New Grenada, in veins in 
 a black bitum.nous limestone, holding ammonites, and of neoco- 
 inian age, its accompaniments being calcite, quartz and carbonate 
 of lantlianum (parisite). Small crystals of emerald are dissemi- 
 nated through this argillaceous somewhat niagnesian limestone, 
 which contains nioreovor a small amount of glncina in a condition 
 
 
90 
 
 19 
 
 soluble in acids. (Lewy, Ann. dc Ch. et Phi/s., liii, 1—20, and 
 Fournet, Geol. Lyonnaisc. 455). 
 
 § 31. To these we may add the production of various hydratcd 
 crystallized silicates, including apophyllite, harmotonie and cha- 
 bazito, during the historic period in the masonry of the old 
 Roman baths at Plombieres and Luxeuil, and by the action of 
 waters at temperatures of from 46^^ to 70^* Centigi-ade ; the 
 presence of apophyllite, natrolite and stilbite in the lacustrine 
 tertiary limestones of Auvergne ; apophyllite incrusting fossil 
 wood, and chabazite crystals lining shells in a recent deposit in 
 Iceland. The association of such hydrated silicates with ortho- 
 clase, as already noticed (§ 13) and as described by Seheercr, 
 where natrolite and orthoclase envelope each other, showing their 
 contemporaneous formation, with many other facts of a similar 
 kind, lead to the conjecture that orthoclase, like beryl and quartz, 
 and perhaps some other constituents of granitic veins, may have 
 crystallized in many cases at temperatures much lower than those 
 determined by Sorby, and that the conditions of their production 
 include a considerable range of temperature ; a conclusion which 
 is however, probably true to some extent, of zeolites also. 
 
 It is proposed to continue the subject of granitic veins, and iu 
 a third part of this paper to give some facts in the history of tlio 
 veinstones of Laurentian rock?.