Report issued by the Bureau of Mines over the Leadville Drainage Tunnel. Descriptions and details about the tunnel are presented. This report includes tables, maps, illustrations, and photographs.

A report about the Sugar Loaf and St. Kevin mining districts located in Colorado. Most of the bedrock consists of pre-Cambian schist, gneiss, granite, and pegmatite.

From abstract: Two hundred and seventy-one prospect pits, mine dumps, or mine workings within the Sugar Loaf-St. Kevin mining districts and vicinity, were tested for radioactivity by the U. S. Geological Survey in 1951 during six weeks of investigation on behalf of the Division of Raw Materials of the U. S. Atomic Energy Commission. One hundred and twenty-two weak radioactivity anomalies were found in the St. Kevin district and vicinity, and eight slight anomalies were noted in"-the Sugar Loaf district, which adjoins the St. Kevin district on the south, Most of the radioactivity anomalies were found in igneous and metamorphic rocks of pre=Cambrian age, but some were found in metalliferous veins of Tertiary age.

Report discussing the results of a six-week geological investigation of 271 prospect pits, mine dumps, and mine workings in the Sugar Loaf -St. Kevin mining districts of Lake County, Colorado during 1951. The objective of the investigation was to determine the presence of radioactive materials.

The following report was prepared in cooperation with the Colorado State Geological Survey Board and the Colorado Metal Mining Fund Board. This report concerns work done partly on behalf of the U.S. Atomic Energy Commission and is published with the permission of the Commission.