COLLECTIONS IN ECONOMIC GEOLOGY AND METALLURGY. 47 



(3) Galena, bleude, pyrite, with a little quartz ; fiue ore, for roaatiug in reverbera- 

 tory furnace. Colonel Sellers Mine, Leadville, Lake County, Colorado. (51075.) 

 Composition the same as No. 51072. 



To illustrate the siliceous sulphurated ores two specimens are shown : 



(1) Quartz, containing small amounts of sulphides and stained by decomposition 

 products, especially carbonates of copper. Eureka Hill Mine, Tintic District, Tooele 

 County, Utah. (51051. ) The composition is as follows : 



Iron (Fe) varies from 3.0 to .5.0 percent. 



Silica (SiO,) varies from 50.0 to 80. percent. 



Sulphur (S) varies from 0. 08 to 2.2 percent. 



Lead (Pb) varies from 5.0 to 8.0 percent. 



Silver (Ag) varies from 30.0 to 60. ounces per ton. 



Gold (An) varies from 0. 05 to 0.08 ounce per ton. 



(2) Quartz and calcite, containing small amounts of sulphides ; crushed ore. Gu- 

 anajuato, Mexico. (51077. ) 



The composition of this ore is as follows : 



^.^ Per cent. 



Sihca(SiOi) ^^y- 



Iron(Fe) 2! 29 



Manganese (Mn) ^^.^^^ 



Alumina (AljOj) rj 03 



Lime (CaO) ^ ^y 



Magnesia (MgO) •• eg 



Sulphate of barium (BaS04) * trace 



zi^'=(zn) "::::;::::::;:::;::::; trace 



Arsemc(A8) ^^^^^ 



Copper (Cu) ^^^^^ 



Antimony (Sb) ^ „r 



Lead(Pb) , [V "..][. 14 



Sulphur(S) ."!.'."!..""..!! l!46 



Carbonic acid (CO/) g .^^ 



Silver (Ag) 855, 75 ounces per ton ' 3.934 



/'7«xes 



To illustrate the iron ore fluxes two samples are shown : 



(1) Consisting essentially of the hydrated sesquioxide of iron (limonite). It is found 

 in connection with the lead ores in the mine, and is probably the result of decompo- 

 sition of the original pyrite in the upper portions of the vein. Besides lead, it also 

 contains a small amount of silver. Madonna Mine, Monarch, Chaffee County, Col- 

 orado. (51053.) A typical analysis of this ore is as follows : 



^^«^(F«) 42. 05 per cent. 



Manganese (Mn) 3. 12 per cent. 



Sili<=^(SiO.) 5.10 percent. 



Zi°c(Z°) 1.86 per cent. 



Sulphur (S) 0.02 per cent. 



^.^•^(P^) 4.0 to9.0percent. 



Silver(Ag) 2 to5.0 ounces per ton. 



(2) Consisting essentially of the hydrated sesquioxide of iron (limonite), but contain- 

 ing a considerable amount of manganese. It is found in connection with the lead ore 

 in the mine and is probably the result of the decomposition of the original pyrite in the 

 Qpper portions of the vein. It contains little or no lead, but a valuable amount of 



