X GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



tion by Messrs. H. Hiiber & Co., F. G. Bulkley & Co., and George H. 

 Robinson & Co., respectively. 



From June, 1880, to June, 1881, my time was partially taken up in 

 tb*^ supervision and direction of experts employed under tbe authority of 

 the Superintendent of the Census in making an investigation into the "Sta- 

 tistics and Technology of the Precious Metals " in the Rocky Mountains. 



From the close of field work in the summer of 1880 to May, 1881, I 

 was mainly occupied with Mr. Jacob in completing the examination of the 

 mines and deposits of Leadville. In this work we received, with a single 

 exception, the most courteous treatment from mine owners and superin- 

 tendents, who not only opened their mines freely to our inspection and per- 

 mitted the use of the maps of their underground workings, but also aided 

 us materially in many cases by the information they furnished from their 

 own every-day experience. To these gentlemen, individually and collect- 

 ively, I return my most hearty thanks, as well for the services above 

 mentioned as for the confidence thereby displayed in the disinterestedness 

 of our motives and our wish to be of service to the mining public in gen- 

 eral without favoring unduly any individual or corporation. 



During the summer of 1881 the individual members of the corps, aided 

 by Messrs. Morris Bien and W. B v. Richthofen, were occupied in collating 

 the results obtained, and in the preparation of the various maps and illus- 

 trations for the engraver, and by autumn the work was so far completed 

 that I was enabled to embody the principal results arrived at in an abstract 

 published in the Second Annual Report of the Director of the Survey. 



During the time that has elapsed since the publication of that abstract 

 the development of the Leadville mines has proceeded with rapid strides, 

 and already the ores are changing from carbonates and chlorides to sul- 

 phides. In other respects also these developments have aff"orded most 

 gratifying confirmation of the general accni-acy of the geological outlines 

 given on the accompanying maps and sections. Even had it been other- 

 wise, it would have been impracticable to have changed what had long since 

 been engraved. In the press of other work it was not possible to attempt 

 another examination of the field, and therefore in the final revision of this 



