Excerpt from A Text-Book of Mineralogy: With an Extended Treatise on Crystallography and Physical Mineralogy The preparation of a text-book Of Mineralogy was undertaken in 1868, by Prof. J. D. Dana, immediately after the publication of the fifth edition of the System of Mineralogy. The state of his health, however, early compelled him to relinquish the work, and he was not able subsequently to resume it. Finally, after the lapse of seven years, the editorship of the volume was placed in the hands of the writer, who has endeavored to carry out the original plan. The work is intended to meet the requirements of class instruction. With this end in view the Descriptive part has been made subordinate to the more important subjects embraced under Physical Mineralogy. 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.