18 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
IIurlburt, E. B. On alunite from Red Mountain, Ouray County, 
Colo.: Am. Jour. ScL, 3d ser., Vol. XLVIII, 1894, pp. 130-131. 
Rickard, T. A. The development of Colorado's mining industry: 
Trans. Am. Inst. Min. Eng., Vol. XXVI, 1896, pp. 834-898. 
Contains brief historical notes on the San Juan region. 
Schwarz, T. E. Discussion of paper by T. A. Rickard: Trans. Am. 
Inst. Min. Eng., Vol. XXVI, 1896, pp. 1056-1060. 
Describes "ore break " of Genesee- Vanderbilt mine. 
Purington, C. W. Preliminary report on the mining industries of 
theTelluride quadrangle, Colorado: Eighteenth Ann. Rept. U. S. 
Geol. Survey, Part III, 1898, pp. 745-850. 
A valuable study of the ore deposits lying immediately west of the Silverton 
quadrangle and including also a few mines, such as the Tomboy, within the 
former area. The general similarity of conditions obtaining within the Silver- 
ton and Telluride quadrangles renders the material of this report specially impor- 
tant, and it will frequently be referred to in the following pages. 
Cross and Purington. The Telluride folio : Geologic Atlas U. S. , 
folio 57; U. S. Geol. Survey, 1899. 
Maps and general geology of the quadrangle adjoining the Silverton quadrangle 
on the west. In this folio are defined and described many of the geological for- 
mations which extend into the Silverton area. 
Engineering and Mining Journal, Vols. XXIII (1877) to the 
present. 
Numerous brief reports from correspondents in the San Juan region. Their 
value at the present time is in their historical data. 
Raymond, R. W. Report on the Mineral Resources of the States 
and Territories West of the Rocky Mountains, Vols. I to VIII, 
comprising the years 1869-1876. 
Contains many notes on the mines of the San Juan. 
Burchard, H. C. Report of the Director of the Mint on the Produc- 
tion of Gold and Silver in the United States, 1880-1884. 
Contains numerous notes on the development and production of the mines in 
the Silverton quadrangle. 
Kimball, James P. Report of the Director of the Mint on the Pro- 
duction of Gold and Silver in the United States, 1885-1888. 
Brief notes on the San Juan region, chiefly in regard to production. 
Leech, E. O. Report of the Director of the Mint on the Production 
of Gold and Silver in the United States, 1889-1892. 
Brief notes on mines, chiefly in regard to production. 
Roberts, George E. Report of the Director of the Mint on the Pro- 
duction of Gold and Silver in the United States, 1897. 
Brief notes on mines and production of region, by counties. 
Lee, H. A. Report of the State Bureau of Mines for 1897; Denver, 
pp. 109-112. 
Gives production for year by counties and some historical data on San Juan County. 
Van Horn, Frank R. Andesitic rocks near Silverton, Colorado: 
Bull. Geol. Soc, America, Vol. XII, 1900, pp. 4-9. 
Petrographical descriptions and chemical analyses of various more or less altered 
specimens from the southeastern quarter of the Silverton quadrangle. 
