The Journal Of Geology Volume 7 PDF Download

Excerpt from The Journal of Geology, Vol. 7: July August, 1899 The vague spheres of feldspar often have an imperfect black cross in polarized light, and consist mainly of orthoclase, some what turbid and specked with brown iron oxide, with a little of the green mineral intermixed. The rest of the rock contains some orthoclase also, but consists chie y of the isotropic substance inclosing the radiating bundles of prisms referred to before. The green prisms are fresh in color and appearance, and are usually distinctly dichroic, dark green when the prism IS parallel to the chief section of the nicol, yellowish-green at right angles to this position. Extinction is nearly parallel, but angles of occur. The larger crystals sometimes have sharpened ends, The mineral was at first taken for hornblende, but is no doubt aegyrite. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."