100 



DESCRIPTIONS OF MINERALS. 



Claudetitc is the same compound in trimetric crystallizations, from 

 Portugal. 



General Remarks. — Arsenic is obtained for commerce chiefly from 

 arsenopyrite.ormispickel), an iron sulpk-arsenide, and from the nickel 

 and cobalt arsenides, by first roasting off the sulphur, and then con- 

 densing the arsenic, in the state of As 2 3 (" arsenous acid ") in large 

 chambers. To obtain the material pure it is usually sublimed again 

 in iron pots, in the upper part of which (artificially kept cool) it is 

 condensed, mostly in a half-fused vitreous condition. To reduce the 

 oxide to the metallic state it is heated with charcoal. In Devon and 

 Cornwall the arsenical ores occur with the tin ore, and a large amount 

 of white arsenic is made. The metal arsenic forms a small part of 

 some alloys ; the most important is that with lead for shot making. 



Native Antimony. 



Rhombohedral ; EaR=87° 35'. Usually massive, with a 

 verv distinct lamellar structure ; sometimes granular. Color 

 and streak tin-white. Brittle. H. = 3-3 -5. G-. = 6 -6-6 *75. 



Composition. Pure antimony, often with a little silver, 

 iron, or arsenic. B. B. on charcoal fuses easily and passes 

 off in white fumes. 



Obs. Occurs in veins of silver and other ores in Dauphiny, 

 Eohemia, Sweden, the Hartz, and Mexico. 



Stibnite. — Gray Antimony. Antimony Sulphide. 



Trimetric. In right rhombic prisms, with striated lateral 

 faces ; I a 7=90° 45'. Cleavage in the direction of the shorter 

 diagonal, highly perfect. Commonly diver- 

 gent columnar or fibrous. Sometimes massive 

 granular. 



Color and streak lead-gray ; liable to tarn- 

 ish. Lustre shining. Brittle ; but thin lami- 

 na? a little flexible. Somewhat sectile. H. =2. 

 G. =4-5-4-62. 



Composition. Sb 2 S 3 = Sulphur 28-2, anti- 

 mony 71-8. Fuses readily in the flame of a 

 candle. B. B. on charcoal* it is absorbed, giv- 

 ing off white fumes and a sulphur odor. 



Diff. Distinguished by its extreme fusibility 

 and its vaporizing before the blowpipe. 

 Obs. Stibnite occurs in veins with ores of silver, lead, 

 zinc, or iron, and is often associated with barite, spathic 

 iron, or quartz. It occurs at Felsobanya and Schemnitz in 

 Hungary ; at AVolfsberg in the Hartz ; at Braunsdorf near 

 Freiberg ; in Auvergne, Cornwall, Spain, and Borneo. 



