G R A 



G R A 



cording to Vauquelin, it consists of alu- 

 mina 45, silica 33, oxide of iron 13, 

 oxide of manganese 4, and lime 4. Its 

 form and infusibility distinguish it from 

 the garnet. 



GRANI'FEROUS. (from yranum and fero, 

 Lat.) Pods which bear seeds like 

 grains. 



GRANILI'TE. An aggregate containing 

 more than three constituent parts ; thus 

 named by Mr. Kirwan. 



GRA'NITE. (granito, It. granit, ou granite, 

 Fr. Pierre fort dure, qui est composte 

 d'un assemblage d'autres pierres de dif- 

 ftrentes couleurs.) An aggregate of 

 felspar, quartz, and mica, whatever may 

 be the size or figure of the several ingre- 

 dients, or their relative proportions, is 

 denominated granite. There are many 

 varieties of granite ; as porphyritic granite, 

 in which large crystals of felspar occur ; 

 sienitic granite, in which hornblende 

 supplies the place of mica ; chloritic, or 

 talcy granite, composed of quartz, fel- 

 spar, and talc or chlorite, instead of 

 mica ; felspathic granite, &c. &c. Gra- 

 nite is a compound plutonic or igneous 

 rock, unstratified and crystalline, of a 

 granular structure, whence its name. 

 From its great relative depth, granite is 

 rarely met with but in mountainous situ- 

 ations, where it appears to have been 

 forced through the more superficial co- 

 vering. " It was at one time supposed 

 that granite was peculiar to the lowest 

 portions of the rocks composing the crust 

 of the earth, and that, in fact, it consti- 

 tuted the fundamental rock upon which 

 all others had been formed, and was not 

 discovered higher in the series. This 

 opinion has given way before facts, for 

 we find granitic rocks in situations where 

 they must have been ejected subsequent- 

 ly to the period during which the creta- 

 ceous group was deposited, as also in 

 other places, into which they must have 

 been thrust at intermediate periods down 

 to the oldest rocks inclusive. Granite 

 is said to contain forty-eight per cent, of 

 oxygen. Granite being an igneous rock, 

 no organic fossil remains could be ex- 

 pected to be found therein, nor have any 

 ever been discovered ; nevertheless gra- 

 nite is occasionally found overlying strata 

 containing fossil organic remains, as in 

 Norway ; a mass of granite has been dis- 

 covered superincumbent on secondary 

 limestone, which contains orthocerata, 

 &c. From these circumstances there can 

 no longer exist a doubt but that granite 

 has been formed at different periods, and 

 is of various ages. A comparatively mo- 

 dern granite may be observed in the Alps 

 penetrating secondary strata, such se- 

 condary strata containing fossils, such as 



belemnites, referrible to the age of the 

 English lias. Felspar is by far the largest 

 constituent of granite, and in some kinds 

 it is found in large whitish crystals of 

 irregular forms, occasionally of one or two 

 inches in length. Granite of this kind, 

 however beautiful it may be to the eye, 

 is not well adapted for buildings, the fel- 

 spar being subject to decomposition from 

 the continued action of the atmosphere. 

 Waterloo-bridge is unfortunately built of 

 this perishable kind of granite. It may 

 be considered as a general law, that 

 wherever granite rises to any height above 

 the surface of the earth, the strata of 

 other surrounding rocks rise towards it. 

 The highest point at which granite has 

 been discovered in any part of the world 

 is Mont Blanc, 15,683 feet above the 

 level of the ocean. Saussure, who has 

 published an account of his ascent of 

 Mont Blanc, infers from his observations 

 that the vertical beds of granite were 

 originally horizontal and have been up- 

 heaved by some violent convulsions of 

 nature, and he states that what now 

 forms the summit of the mountain must 

 at some former period have been more 

 than two leagues below the surface. 

 GRA'NITEL. > A name given by Kirwan to 

 GRA'NITELL. 5 a binary aggregate com- 

 posed of any two of the following ingre- 

 dients : felspar, mica, shorl, quartz, gar- 

 net, steatites, hornblende, jade. 

 GRANI'TIC. Composed of grains or crys- 

 tals united without a cement, as in gra- 

 nites and some sandstones. 

 GRANI'TICAL. Consisting of granite ; com- 

 posed of granite. 



GRANI'TIC AGGREGATE. A granular com- 

 pound, consisting of two, three, or four 

 simple minerals, among which only one 

 of the essential ingredients of granite is 

 present. Among the granitic aggregates, 

 which contain only one of the essential 

 ingredients of granite, may be enumerated 

 combinations of quartz and hornblende, 

 quartz and actinolite, felspar and 

 schorl, mica and hornblende, quartz, 

 hornblende, and garnet, quartz, horn- 

 blende, and epidote, &c. &c. 

 GRANITIFICA'TION. The act of being 



formed into granite. 

 GRANI'TIFORM. Resembling granite in 



structure or shape. 



GRA'NITINE. An aggregate of three mi- 

 neral constituents, one or more differing 

 from those which compose granite. For 

 example, an aggregate of quartz, fel- 

 spar, and shorl is a granitine, as is one of 

 quartz, mica, and shorl; or quartz, horn- 

 blende and garnet ; and many others. 

 GRANI'TOID. (from granite and tiBoc, Gr.) 



Resembling granite. 

 GRANI'VOROUS. (from yranum and voro, 



