An historical, in-depth survey of one of the most important mining districts in the US at the time. Digital PDF download. GEO-1886-01D
From the Preface:
The present work was undertaken at the instance of the Hon. Clarence King, first Director of the United States Geological Survey, in 1879. It was his intention that it should form part of a series of monographs which would in time include all the important mining districts of the country, and thus furnish an accurate and permanent record of the manner of occurrence and geological relations of the metallic deposits of the United States, as well as of all substantial improvements in the methods of obtaining the metals from their ores.