GRANITE. 



lace of granitic mountains, and in tlie immediate vicinity of 

 veins. Granite, with fcldfpar thus converted into an earthy 

 ftate, is found in Cornwall, on the Hartz, at Biirkardi- 

 griin in Saxony, &c. ; and it is probable to Mr. Emmer- 

 lingthat the giefs-llein, (Saxuni fuforium, Linn ) which, on 

 account of its loofe texture, is made ufe of in the brafs foun- 

 deries of Sweden and France, may be granite in a fimilar 

 ftate of incipient decompofition. Alfo, the mica is fubjeft 

 to difmtegration, efpecially when adted upon by fubterrane- 

 ous water and vapours ; the mafs into v.hiih it is thus con- 

 verted is confidercd as being of the nature of ftcatite. In 

 this ftate it is found at Fichtelberg, in the Upper Palati- 

 nate, and in the vicinity of Toriiitz, near Carllbad, in 

 Bohemia. 



Befides feldfpar, quartz, and mica, other foflils are found 

 admixed, which, not being confidered as eftential, are generally 

 diftingui(hed by the appellation of acciJen/al ingredients. Tliey 

 are, l . Shorl ; the moft frequent of all. It occurs m?frive 

 and diffeminated, iometimes alio cn-ftal!ized, and appears 

 principally to belong to the old granite -formation : it is 

 found in feveral parts of Saxony, in Lower Bavaria, Uppef- 

 Palatinate, Wirtenberg, Tranfylvania, Cornwall, &c. ; 

 2. Garnet : moftly in fniall grains. It occurs but rarely ; 

 but has been found near Leipzig (in boulders), at the Grei- 

 fenftein, and in the neighbourhood of Voigtsdorf, in the vici- 

 nity of Freiberg, in Saxony, in Lower Bavaria, &c. An 

 aggregate of quartz, mica, and garnets, is by the Swedes 

 called norka or murkften. 3. Tinftone ; frequent in the 

 granite of Geier, Zinnwald, &c. 4. Nephrit or jade ap- 

 pears to occur not only in gneifs, but alfo with real granite, 

 in Switzerland. 5. Rock cryftal. 6. Beryl ; in the ifiand 

 of Alba, and perhaps alfo in Siberia. 7. White common 

 opal, fometimes occurs in the granite of Eibenftock in 

 Saxony. 8. Topaze is fometimes feen, together with tin- 

 ftone, in the granite of Zinnwald. 9. Calcareous fpar, 

 very feldom. 10. Fluor-fpar, the fan.e ; in Siberia, at 

 Geier in Saxony. 11. Barytes, equally feldom; in Swit- 

 zerland. 



Foreign beds are lefs frequently met with in granite than 

 in other rocks. The more remarkable ones are thofe of 

 tin-ftone, galena, and blende at Zinnwald on the Bohemian 

 frontiers ; the beds of mica, particularly in Silefia and 

 Lufatia ; of quartz, and rock cryllal in Switzerland. Alfo 

 beds of feldfpar are faidto occur m it. The green feldfpar, 

 called Amazon ftone, is found in large malfes in the grani5e 

 of the Ural mountains of Siberia. 



Stralification of Granite. — Though granite occurs frequent- 

 ly as widely-extended mafies, in which tlie eye is unable to 

 difcover any continued traces of parallel feparation ; yet 

 there can be no longer any doubt that thofe geologilts, who 

 abfolutely denied the exiftence of ftratified grariite, were 

 either entirely unacquainted with the flrufture of many of 

 the European granitic mountains, or too much influenced 

 by the principles of their favourite theories, to allow the 

 obferved traces of demarcation to ba any thing but irregiJar 

 and accidental rents and fiftures. Pini even endeavours, 

 by mathematical figures, to prove the impoffibility of itra- 

 tification in granite. Notwithftanding all this, the ob- 

 fervations of the moft eminent gcologifts appear to 

 prove that fuch ftratification, even iji the Itrifteft fenfs of 

 the word, is not uncommon ; but it is often a matter of great 

 difficulty, for an eye, unaccuftomed to viewing tlie ftructure 

 of mountains on a large fcale, to dillinguilli the parallelilm, 

 or to follow the obfcurely marked progrefs of the line of le- 

 paration of the ftrata, efpecially when they aic of conlidcr- 

 ablc thicknefs. 



But in many cafes, it would appear tliat this ftratification 



18 too diftinft to leave any doubt upon the mind of the ob- 

 fervcr. Nothing can be more convincing than the recount 

 given by Gruber of the ftratified nature of the granite 

 compofing the Riefengebirge, that fcparate* Silefia from 

 Bohemia. The rocks that chiefly compofc this celebrated 

 range of mountains arc granite and gneifs, which, on the 

 higheft point.", fuch as the Riefen and Schnce-kuppe, are 

 feen ill fourfold alternation. Mr. Gruber has afcertaincd the 

 dip and dircftion of the ftrata in eight places, and proved 

 them to be perfectly dillin£l from the rents which fare fre- 

 quently feen nearly at right angles with the lines of ftratifi- 

 cation. 



P'rom Saufture's obfervations, made on the feveral grani- 

 tical pyramids or " aiguilles'" of the Mont-Blanc, it would 

 appenr that all the parts of this mojiitain are compofed of 

 vail layers of granite perpendicular to the horizon, anddi- 

 reCled from N.E. to S E. Still more diftinct this ftrati- 

 fication appears on Mount St. Gothard. (See Goill.VKD.) 

 According to Charpcnlier, Lcfl;e, and others, alfo the granite 

 of the whole of U])per Lufatia, and of feveral parts of 

 Saxony, aff?Cts the llratiiied ilruClure. 



In a fimilar manner Mr. Gruber obferved the regular 

 ftratification near Car!ft)ad and Teplitz ; and Dr. Reufs 

 found the fame in feveral other parts of Bohemia ; fuch as.in 

 the Eger diilrict, where the ftrata dipped north at an angle of 

 18' ; in the Saatz diftrict at Lefchkau ; in the Leutmeritz 

 dilti id on the Saxon frontiers ; at the Wolfsberg, where the 

 ftrata run from two to fix feet in thicknefs ; as alfo in feveral 

 places in the diilrirt of Buntzlau, towards the Riefengebirge. 

 La Peroufe defcribes the granite of part of the Pyrenees 

 as difpofed in layers or beds. 



In the north of Europe, fimilar regularity appears to 

 prevail in the ftratification of granite ; thus, according to 

 Croiiftedt and others, in Sweden, on the Kinnekulle and 

 Billing, in Weft GotlJand, the granite (confifting mcftly of 

 red feldfpar, white quartz, and black and greenifti mica, in 

 nearly equal proportion ) is obferved in diftinft layers, with 

 fuperincumbent ftrata of rocks of fublequent formation. 



P.illas followed vaft and continuous layers of granite through 

 whole t rafts of mountains in Siberia : indeed, part of the 

 granitic Ural mountains, in the neighbourhood of the lake 

 Kolywan, are defcribed as having the appearance of huge 

 artificial ftruftures, in which the layers appear to be loofely 

 piled on one another. 



Dr. Hutton fuppofed granite, when not ftilftofe in it« 

 ftrufture, to be altogether unftratified ; profcflbr Plav-fair, 

 however, in his expofition of the Plutonic fyftem, fo far differs 

 from the opinion of liis ingenious friend, that he allows gra- 

 nite to form ftrata alfo where it has no charaftcr of gneifs; 

 and he thinks that this admiflion does not cmbarrafs the 

 theory with any new difficulty ; but, on the other hand, he fuf- 

 peCis that the ftratification afcribed by the Neptunifts to the 

 granite mountains is, in many inftanccs, cither an iilufion, or 

 at leaft fomething very difierent from what, in other ftoncs, 

 is accounted ftratification. Profeflbr Playfair found ftrati- 

 fied granite, in England, at Chorley Foreft, in Leicefter- 

 ftuie,^where, particularly near Mount Sorrel, beds of granite 

 are feen, holding the fame direcliou with thofe of the lub- 

 jacent " horn-ftone fcliiftus ;'" and likewife at Faffiiet-watcr 

 in Berwickfhire, where the beds of granite run from about 

 S S.W. to N.N.E. conformable to the fchiftus on either fide 

 of them. Rcfpefting the granite mountains of Arran, we have 

 it oblerwd by tl-e fame philofopher that this ftratifica- 

 tion appears doubtful. The mountain of Goatficld, in that 

 intcreftingilland, appeared, contrary to what Mr. Jaincfonhad.. 

 advanced in his " Mineralogv- of the Scottifti I lies," without- 

 aiiy veftige of llratilkation in its granitic part, as didalfo the 



whole 



