Mineral deposits

Mineral deposits are usually classified and described by the metals or the substances which they contain; for instance, deposits of copper are described together, with little or no effort to separate them into genetic groups. Where a genetic treatment has been attempted it appears to me to have failed in not giving due weight to the physical conditions attending the genesis. Furthermore, it is the custom to divide the mineral deposits into two groups—the metallic and the non-metallic—a line of division which can hardly be defended except on the ground of long-established habit.

This book is the outcome of a desire to place the knowledge of mineral deposits on the broader and more comprehensive basis of a consistent genetic classification and thus bring it into a more worthy position as an important branch of geology. Opinions may differ as to whether our present knowledge is sufficient for such an undertaking. Believing that the time has come for a first attempt, I present this volume, in the hope that its shortcomings may be judged leniently.

The impetus of the work came during the preparation of a series of lectures a few years ago, and a course along the general lines followed in this volume has since then been presented annually at the Massachusetts Institute of Technology.

The general plan has been to select a few suitable examples to illustrate each genetic group of deposits. These examples have been chosen regardless of their geographic location, and it was of course necessary to give up any attempt to describe deposits in detail or to present all known examples of any particular type. As the larger part of my experience has been within the United States of America, a considerable number of examples were gathered from this country. This experience I owe to the United States Geological Survey, in which I have had the honor to serve for many years. My indebtedness to my friends and associates in that organization is greater than can be expressed in words.