This bulletin has been prepared primarily with a view to securing prompt publication of the economic results of investigations by the United States Geological Survey. It is designed to meet the wants of the busy man, and is so condensed that he will be able to obtain results and conclusions with a minimum expenditure of time and energy. It also affords a better idea of the work which the Survey as an organization is-carrying on for the direct advancement of mining interests throughout the country than can readily be obtained from the more voluminous reports. Should this bulletin be favorably received by those interested in the development of the mineral industries of the United States, it is proposed to publish early in each calendar year a similar bulletin containing the results of the last year's field work in economic geology.

In the preparation of the present volume, promptness of publication has been made secondary only to the economic utility of the material presented. The papers included are such only as have a direct economic bearing, all questions of purely scientific interest being excluded.

The papers represent three classes : (1) Preliminary discussions of the results of extended economic investigations, which will later be published by the Survey in more detailed form; (2) comparatively detailed descriptions of occurrences of economic interest, noted by geologists of the Survey in the course of their field work, but not of sufficient importance to necessitate a later and more extended description; (3) abstracts of certain economic papers which have appeared in Survey publications during the last year, chiefly such as give a general account of the distribution and mode of occurrence of particular mineral deposits throughout the United States.

The papers have been grouped according to the subjects treated. At the end of each section is given a list of previous publications on that subject by this Survey. These lists will be found serviceable by those who wish to ascertain what has been accomplished by the Survey in the investigation of any particular group of mineral products. They are generally confined to Survey publications, though a few titles of important papers published elsewhere by members of the Survey are included.