146 DESCRIPTIONS OF MINERALS. 



Composition. Pb S= Sulphur 13*4. lead 86-6 = 100. Often 

 contains some silver sulphide, and is then called argentifer- 

 ous galena ; and at times zinc sulphide is present. The ore 

 of veins intersecting crystalline metamorphic rocks is most 

 likely to be argentiferous. The proportion of silver varies 

 greatly. In Europe, when it contains only 7 or 8 ounces 

 to the" ton it is worked for the silver. The galenite of the 

 Hartz affords -03 to -05 per cent, of silver ; the English '02 

 to '03 per cent. ; that of Leadhills, Scotland, *03 to '06 ; 

 that of Pike's Peak, Colorado, *05 to '06; that of Arkan- 

 sas, -03 to '05 ; that of Middle-town, Ct., 15 to '20 ; that of 

 Poxbury, Ct., 1*85 ; that of Monroe, Ct., 3*0 ; while that of 

 Missouri afforded Dr. Litton only -0012 to -002? per cent. 

 A little antimony or cadmium is sometimes present. 



B.B. on charcoal, it decrepitates unless heated with cau- 

 tion, and fuses, giving off sulphur, coats the coal yellow, 

 and finally yields a globule of lead. 



Biff. Galenite resembles some silver and copper ores in 

 color, but its cubical cleavage, or granular structure when 

 massive, will usually distinguish it. Its reactions before the 

 blowpipe show it to be a lead ore, and a sulphide. 



Oos. Galena occurs in granite, limestone, argillaceous 

 and sandstone rocks, and is often associated with ores of 

 zinc, silver and copper. Quartz, barite, or calcite is gener- 

 ally the gangue of the ore ; also at times fluor spar. The 

 rich lead mines of Derbyshire and the northern districts of 

 England, occur in the Subcarboniferous limestone ; and the 

 same rock contains the valuable deposits of Bleiberg, in 

 Austria, and the neighboring deposits of Carinthia. The 

 ore of Cornwall is in true veins intersecting slates and is 

 argentiferous. At Freiberg in Saxony, it occupies veins in 

 gneiss; in the Upper Hartz, and at Przibram in Bohemia, 

 it traverses clay slate, of Lower Silurian age ; at Sahla, 

 Sweden, it occurs in crystalline limestone. There are other 

 valuable beds of galena, in France at Poullaouen and Huel- 

 goet, Brittany, and at Yillefort, department of Lozere ; in 

 Spain in the granite and argillyte hills of Linares, in Cata- 

 lonia, Grenada, and elsewhere ; in Savoy; in Netherlands at 

 Vedrin, not far from Xamur ; in Bohemia, southwest of 

 Prague ; in Joachimstahl, where the ore is worked princi- 

 pally for its silver ; in Siberia in the Daouria Mountains in 

 limestone, argentiferous and worked for the silver. 



The deposits of this ore in the United States are remark- 



