GUIDE TO THE MIXERALOGIC COLLECTIONS 



53 



ular grouping. Distorted crystals are frequent, as in the speci- 

 mens from Gonderback, Nassau (N. Y. state museum collection). 

 Twin crystals are also common. Galena is lead-gray in color 

 and streak; it is soft (H-2.5) and very heavy. The luster is 



Fig. 161 



Fig. 163 



metallic and bright on a fresh fracture but apt to become dulled 

 and oxidized on crystal faces which have been long exposed. 



Galena is very widely distributed. It occurs in veins in 

 crystalline and noncrystalline rocks and is commonly associated 

 with other sulfids and other salts of lead, which latter are 

 frequently the result of its alteration. In addition to numer- 

 ous and important foreign localities it occurs in the United 

 States in extensive deposits in Missouri; also in Illinois, Iowa, 

 Wisconsin, and in New York at Rossie, St Lawrence co., Ellen- 

 ville, Ulster co. and Wurtzboro, Sullivan co. 



Galena is the principal ore of lead and is extensively worked 

 in Colorado, Idaho, Montana and other western states for the 

 silver it usually contains. 



Argentite (silver glance) AgS 



The sulfid of silver contains 12.9^ sulfur and 87.1$ silver. 



The crystals are isometric, of an octahedral habit, and are 

 often modified by the cube; distorted forms are quite common as 

 are parallel groupings which produce arborescent forms. It 

 also occurs massive Argentite is soft and sectile; it has a lead- 

 gray color and metallic luster. 



It occurs at Freiberg, Germany; in Hungary, Norway, Corn- 

 wall, Peru, Chile and Mexico. In the United States it is found 

 in Nevada and Arizona and in the Lake Superior region of 

 Michigan. It is mined for silver. 



