326 METALS. 



Stromeyerite. This is a steel-gray sulphuret of -silver and coppei 

 containing 52 per cent, of silver. Gr=626. Before the blowpipe i' 

 fuses and gives an odor of sulphur ; but a silver globule is not obtained 

 except by cupellation with lead. A solution in nitric acid covers a 

 plate of iron with copper, and a plate of copper with silver indicating 

 the copper and silver present. From Peru, Siberia, and Europe. 



Sternbergite. A sulphuret of silver and iron containing 33 per cent, 

 of silver. It is a highly foliated ore resembling graphite, and like it 

 leaving a tracing on paper ; the thin laminae are flexible and may be 

 smoothed out by the nail. Luster metallic, color pinchbeck brown. 

 Streak black. It affords the odor of sulphur and a globule covered 

 with silver on charcoal, before the blowipe. With borax a globule of 

 iilver is obtained. From Joachimstahl, in Bohemia. 



tjVe brittle silver ore. — Sulpkuret of Silver and Antimony. 



Trimetric. In modified right rhombic prisms. M: M= 

 115° 39. No perfect cleavage. Often in compound crys- 

 tals. Also massive. 



Luster metallic ; streak and color iron-black. H = 2 — 2'5. 

 Gr = 6-27. 



Composition : Sulphur 16*4, antimony 14*7, silver 68*5, 

 copper 0*6. Before the blowpipe it gives an odor of sulphur 

 and also fumes of antimony, and yields a dark metallic glob- 

 ule from which silver may be obtained by the addition of 

 soda. Soluble in dilute nitric acid, and the solution indi- 

 cates the presence of silver by silvering a plate of copper. 



Dif. The black color of this ore distinguishes it from 

 the preceding ; and more decidedly the fumes of antimony 

 given off before the blowpipe. By the trial with nitric acid 

 as well as by soda and the blowpipe, it is ascertained to be 

 an ore of silver. 



Obs. It occurs with other silver ores at Freiberg, Schnee- 

 berg, and Johanngeorgenstadt, in Saxony ; also in Bohe. 

 mia, and Hungary. It is an abundant ore in Chili, Peru, 

 and Mexico. It is sometimes called black silver. 



An antimonial sulphuret of silver is said to occur with 

 native silver and native copper, at the copper mines in 

 Michigan. 



Uses. This is a very important ore for obtaining silver, 

 especially at the South American mines. 



Besides this there are other afflgnonial, and also arsenical and sele- 

 iferous ores of silver. «> 



What is the composition of brittle silver ore ? its color and appear* 

 nee ? For what is it valued ? 



