SULPHUR AND ITS COMPOUNDS. 35 



silver in it amounts to 30 per cent., and then it is called 

 argentiferous gray copper ore. 



52. Sulphuret of Lead. The common name of this min- 

 eral is galena. Its crystals are in the form of the cube 

 and its secondaries. Its color is lead-gray, and its lustre 

 is sinning. There is often sulphuret of silver incorpo- 

 rated with it, and it is then called argentiferous galena. 

 It is the ore from which the metal lead is obtained, na- 

 tive lead being exceedingly rare. I have told you how 

 the galena is freed from the sulphur in Part II., 193, 

 and in 210 how the silver is obtained from the galena 

 when it is argentiferous. There are vast quantities of 

 galena iu various parts of the United States, especially in 

 Missouri, Illinois, Iowa, and Wisconsin. It is so abund- 

 ant in the last-named state that the miners seldom take 

 the trouble to get out the ore deeper than twenty-five or 

 thirty feet. Three millions of pounds have been obtained 

 from one spot which is not over fifty yards square. 



53. Sulphuret of Silver. This mineral, commonly called 

 silver glance, occurs in the form of the dodecahedron and 

 its secondaries. Its color is lead-gray, and it has a me- 

 tallic lustre. There is also a sulphuret of silver and an- 

 timony, which is of a black color, and therefore is some- 

 times called black silver. There is also a sulphuret of 

 silver and iron, and one of silver and copper. 



54. Sulphuret of Antimony. This sulphuret appears in 

 prisms, and has a gray color and metallic lustre very much 

 like those of galena. It is the ore from which is obtained 

 nearly all the antimony of commerce. There are also 

 some sulphurets of lead and antimony combined together. 



55. Sulphurets of Arsenic. There are two sulphurets 

 of arsenic. One is of a red color, is translucent, some- 

 times transparent, and its crystals are usually in the pris- 

 matic form. It is called realgar. The other, called or- 

 piment, is of a lemon-yellow color. Both are used as 

 pigments, and also as coloring substances in pyrotechnic 

 mixtures. They are obtained chiefly in Koordistan and 

 China. 



