COLLECTIONS IN ECONOMIC GEOLOGY AND METALLURGY. 39 



composition, the lead decomposition products are generally quite free 

 from zinc. 



The collection to illustrate silver-lead ores begins with galena (the 

 original lead mineral) as pure as possible, and shows its different modes 

 of occurrence; it is then followed on through increasing inijiurities to 

 the commencement of decomposition, and this is followed through until 

 we have as the final state the carbonate of iead (cerussite). 



(1) Galena, iu rough crystals, showing the characteristic cubic cleavage in great 

 perfection. Ohl Story Mine, Georgetown, Clear Creelc County, Colorado. (6^05.) 



(2) Galena, showing coarse cubic cleavage. Washington Mine, South Mountain 

 district, Owyhee County, Idaho. (14817.) 



(3) Galena, showing coarse cleavage, with a little pyrite. North Pacific Mine, Ten- 

 Mile district, Lewis and Clarke County, Montana. (10896.) 



(4) Galena, showing medium cleav.age. Belle of Belleville Mine, Colorado dis- 

 trict, Jefferson County, Montana. (lOSf^G.) 



\^5) Galena, a mixture of fine and coarse cleavage, showing also a little blende. 

 Moose Mine, Park County, Colorado. (39(513.) 



(G) Galena, showing fine cleavage, with a little pyrite. Canon Mine, Lump Gulch 

 district, Jefferson County, Montana. (10902.) 



(7) Galena, showing fine cleavage. Yosemite Mine, Bingham, Salt Lake County, 

 Utah. (18000.) 



(8) Galena, showing fine-grained cleavage, also a beautiful tarnish. Consolidated 

 Gregory Mine, Colorado district, Jefferson County, Montana. (10912.) 



(9) Galena, showing very fine cleavage. Argentine Mine, Colorado district, Jef- 

 ferson County, Montana, (10887.) 



(10) Galena, blende, and pyrite, with a little quartz. Keystone Mine, Park County, 

 Colorado. (39773.) 



(11) Galena, with much blende and a little pyrite. Hiawatha Mine, Chaffee 

 County, Colorado. (3G679.) 



(12) Galena and pyrite. Grecian Bend Mine, Bingham, Utah. (1471.5.) 



(13) Galena, with much pyrite and a little chalcopyrite. Buckhorn Mine, Carlisle 

 district, Boulder County, Colorado. (19131.) 



(14) Galena, with a little blende and some pyrite. Idaho Mine, Boulder County, 

 Colorado. (39497.) 



(15) Galena, blende, and quartz. Hercules and Roe Mine, Clear Creek County, 

 Colorado. (39790.) 



(IG) Galena, blende, and quartz, with a little pyrite and tetrahedrite. Hiawatha 

 Mine, Chaffee County, Colorado. (39690.) 



(17) Galena, with a little pyrite and blende, in quartz. Hathaway Mine, Potoai 

 district, Madison County, Montana. (11048.) 



(18) Galena, in quartz with barite. Mammoth Mine, Hot Springs district, Jeffer- 

 son County, Montana. (10997.) 



(19) Galena, showing coarse cleavage, beginning to decompose. First National 

 Mine, Stockton, Tooele County, Ut:ih. (14744.) 



(20) Galena, showing fine cleavage;, beginning to decompo.se. Little Chief Mine, 

 Leadville, Lake County, Colorado. (32496.) 



(21) Galena, showing decomposition products, including crystals of gypsum on the 

 outside. First National Mine, Rush Valley district, Tooele County, Utah. (14647.) 



(22) Galena, showing decomposition products stained with iron. Miller Mine, 

 American Fork district. Salt Lake County, Utah. (65370.) 



(23) Galena, with a little pyrite, showing decomposition products. Richmond Mine, 

 Eureka district, Eureka County, Nevada. (15530.) 



(24) Galena, showing decomposition products. Keraptou and Neptune Mine, Bing- 

 ham Canon, West Mountain district. Salt Lake County, Utah. (18065.) 



