Author: F. Lewinson-Lessing

Publisher:

Published: 2015-07-22

Total Pages: 66

ISBN-13: 9781331967446

Excerpt from Tables for the Determination of the Rock-Forming Minerals: With a Chapter on the Petrological Microscope There is probably no branch of geology in which an unaided student has more difficulty in making a start than in the microscopic study of rocks. This is especially to be regretted, as it is now recognised that this method of research is indispensable for any accurate work on the igneous rocks. Many a resident on the great volcanic plateaux of India, Africa, or America, or on the vast tracts of gneiss and schists which form such a large proportion of the earth's crust, is debarred from geological work by the difficulty of identifying minerals under the microscope. Thus our knowledge of many of these areas is very deficient, for they are only known by occasional rapid traverses; and the problems they present are so complex that they can only be fully worked out by a resident or by a thorough survey. Elementary students feel the difficulty, though they have the advantage of personal instruction. Probably every one who has tried elementary teaching in geology has felt the need of some simple book of reference. The elaborate tables of Rosenbusch and Michel Levy and Lacroix are, of course, perfect in their way, but they are really summaries of the characters of the minerals rather than guides to their rapid determination. With these, if one knows the name of a mineral, its characters can be at once ascertained; but what the student usually requires is the reverse process. He can recognise the characters of a mineral by the microscope, and from these he wants to know its name. The previous tables afford little assistance in doing this. Professor L winson-Lessing has now supplied this want by a set of tables arranged on what may be called the "dichotomous method." 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."