Minerals and rocks; the elements of mineralogy and lithology for the use of students in general geology
William Shirley Bayley
Paperback
(RareBooksClub.com, May 12, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 Excerpt: ...blowpipe, they exfoliate and fuse on their edges. In the closed tube, all yield water when strongly heated. HC1 attacks them with difficulty; H2S04 with ease. They are distinguished by their cleavage, color, softness, solubility in H2S04 and manner of occurrence. They are found as constituents of partially altered igneous rocks, and of schists. Chlorite schists are made up largely of chlorites and quartz (No. 34). The chlorites also fill veins, and form pseudomorphs after other minerals. 101. Leucite (KAl(Si03)2), is an important rock constituent. It occurs almost exclusively in isometric crystals, resembling those of garnet (Fig. 63), or in small round grains. It is white or light gray, with a glassy luster, and a white streak. It is brittle and transparent or translucent, and has a hardness of 5-6 and a sp.gr. of 2.5. Because it easily Fig. 63.--Leucite decomposes, most specimens appear Crystal, white and opaque. Before the blowpipe, leucite is infusible, but colors the flame for K. It is soluble in HC1 with the production of pulverulent silica. Its powder reacts alkaline. Leucite is distinguished from most other minerals by its crystallization. It is distinguished from white garnet (No. 88) by its inferior hardness and from analcite (No. 130) by its infusibility and the fact that it contains no water. Moreover, analcite fails to give the flame reaction for K (p. 144). The mineral occurs principally in igneous rocks, especially lavas that are rich in potash. It has no commercial value at the present time, but it has been suggested that it might be made a source of potash salts. 102. Kyanite, cyanite ((A10)2Si03) or disthene is an abundant component of some schistose rocks. The name, "kyanite", suggests the sky-blue, color noticed in many specime...