Book Description

Excerpt from The Journal of Geology, Vol. 21: A Semi-Quarterly Magazine of Geology and Related Sciences; January-December, 1913 The past half-century has been a period of rapid development of mines and mining, both in America and in other countries, and as a consequence, ' the basal facts regarding the occurrence Of ores are now comparatively well understood. The geologic causes for the location Of ore-bodies in certain zones or horizons are in many cases known, and many former theories are generally accepted as facts. The transportation of ores by aqueous solutions, the origin of some of these solutions in cooling igneous magmas, and the secondary enrichment of many ore-bodies through the agency of meteoric waters; such are some of the ideas which have withstood prolonged criticism and have become established tenets Of geologic faith. But beyond basal facts, adduced almost solely from field evidence, our knowledge of the mechanism of ore depositions is somewhat vague and unsatisfactory. Only prolonged investigation along chemical and physico-chemical lines will render possible a reasonably accurate understanding of the complex com position oi ore-bearing solutions, of the reactions of these solutions with the wall rocks, of the causes for the deposition of minerals from them, and of many other problems connected with the depo sition of ores. 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.