granIte

& a. [Ital. granito, as s.=granite, as adj. grained, from Lat. granum =a grain, Port. granito; Fr. gran it; Sp. granate. So named because the rock has a coarse granular structure.] A. As substantive : I. Ordinary Language : 1. In the same sense as II. 1. 2. Anything very difficult to be destroyed, as when an individual is said to have a constitution of granite. II. Technically : 1. Petrol . & Geol .: An unstratified rock, normally consisting of three simple minerals, felspar, quartz, and mica, or, in Dana's nomenclature, of orthoclase, quartz, and mica. For a long time the universally accepted view, which is still the prevalent one, was that it is an "igneous" rock, of a "plutonic" type. The difficulty has, however, to be encountered that it is not seen in proce of for mation on the earth's surface. This has been met by the hypothesis that it originates beneath the surface and under high pre ure, produced in most cases by earth, but in some instances by a weight of incumbent water. Like surface volcanic rocks it has been fused and afterward cooled; but it does not, like them, comprehend tuffs and breccias, ., but a umes a crystalline texture, destitute of pores, or cellular cavities to which gases entangled lava or any such rock give rise. It is in favor of its igneous org in that it has in many places broken through ordinary sedimentary or metamorphic strata, sending veins through them in various directions. It rarely, however, overtops or caps them, as if coming up molten through a crater it had overflowed them above. Hence the term proposed for it-" underlying"-to distinguish it from the vol. canic rocks, called "overlying" rocks. Some geologists consider it not an "igneous" or "plutonic," but a metamorphic rock, more altered than gnei , which agrees with it in composition, but in which stratification has not been obliterated. The two views are not nece arily antagonistic; some gran ites may have the one origin and others the other. broken up the strata during Tertiary times. GranIt is of all ages, some granite in the Alps having ite incloses fluid cavities, having in them water, containing chlorides of pota ium and sodium, with sulphates of potash, soda, and lime. 2. Chem., .: M. Duroc her supposes that a ma containing in combustion silica, alumina, alkaline, and earthy bases, potash, soda, sometimes lithia, with a little lime magnesia, the oxides of iron and manganese, with minute quantities of hydrofluoric, and even of boracic acid, would, as it cooled, sep. arate into quartz, mica, and felspar, the felspar crystallizing sooner than the quartz, which would long remain in a viscous state. 3. Physical Geog., Scenery, .: Granite often constitutes the axis of high mountain chains; the Sinaitic range has an axis of granite. Granite hills have a peculiar rounded form, with a scanty vegetation. They are easily distinguishable from the flat topped precipice-flanked basaltic hills. Von Buch considers that granitic mountains so much tend to be portions of a sphere, that he looks upon them as ellipsoidal bubbles, which were forced upward only in a partially fluid state; then, when the upper dome-shaped surface contracted, many granitic blocks were formed. 4. Comm., .: Granite is of much economic value as a building stone. New Hampshire is popularly called the Granite State, on account of the quan tity of granite composing its mountains. [GRANITE POLISHING.] B. As adjective: granivorous II. Fig .: Resembling granite in any of the qualities for which that material is noted. "So up thy hill, ambrosial Richmond! heaves Dull Maurice all his granite weight of leaves: Smooth, solid monument of mental pain." Byron: English Bards and Scotch Reviewers. granite-dispersing, a. Geol.: Dispersing granite in the form of erratic blocks. "The granite- dispersing power of Kirk cud brights hire." -Quar. Jour. Geol. Soc., xxxv. 481. granite-dispersion, s. Geol.: The act of dispersing or scattering granite in the form of erratic blocks. "The great Kirk cud brights hire granite - dispersion ."Quar. Jour. Geol . Soc ., xxxv. 431. granite-group, s. Petrol.: A group of rocks of which granite is the type, arranged under the cla Crystalline Rocks. Rutley includes in it the following species: granite, porphyritic granite, felstone, granitite, cordierite granite, luxullianite, aplite or haplite, granulite, greisen, gnei , protogine, and cor nubia nite (q. v.). granite-polishing, s. The polishing of granite. The method of doing this was discovered by Mac Donald of Aberdeen, Scotland.