A Preliminary Report On A Part Of The Granites And Gneisses Of Georgia PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 edition. Excerpt: ...--Silica, SiO 2 69.43 Alumina, AI2Oj 16.64 Iron Sesqui-oxide, Fe 10 3 1.84 Lime, CaO 2 32 Magnesia, MgO 0 29 Soda, Na20 4-74 Potash, K20 4 49 Ignition o 46 Total 100.26 A total of 10.81 per cent, of soluble matter was extracted from a weighed quantity of finely pulverized rock, after digestion for three hours in boiling half-normal hydrochloric acid. Absorption tests made on specimens of this rock gave the following figures: --Percentage (ratio) of absorption 0.049 The figures indicate a minimum absorption for this rock. The rock quarried has been used mostly for monumental stock. 1 Tabular in the direction of the clinopinacoid (010). The Mack1n Property.--This property contains some three or four acres of flat-surface outcrops, exposed in one mass, and located from one and three-quarters to two miles northeast of Sparta, and about half-a-mile from, and on the north side of, the Georgia railroad. Two months previous to the writer's visit, one small opening was made in the outcrop, revealing a coarse-grained porphyritic granite, carrying an abundance of feldspar. A dike of very fine and even-grained biotite granite, nine feet in width, cuts the porphyritic mass, and is well exposed in the opening. The rock of the porphyritic mass is, in all respects, the same as that quarried at the Sparta quarry, with the exception that the feldspars are somewhat deeper in color, and more prevailingly pink or fleshcolored. In the rock from the quarries in this county, hitherto described, the feldspar phenocrysts are usually white and opaque; while they are prevailingly pink from the Mackin place. The pink, tabular phenocrysts are from 15 to 20 millimeters long, parallel to the clinopinacoidal direction, and are twinned according to the Carlsbad law. They...