502 ARSENIC. Constituent Parts. Besides arsenic and iron, it contains from .01 to 0.19 parts of silver. Geognostic and Geographic Situations. Its geognostic situation is the same as that of common arsenic pyrites, with which it is usually associated. It is also accompanied with dark red silver-ore, galena or lead- glance, and copper-pyrites; sometimes with white silver- ore, brown blende, and generally with quartz and brown- spar. It is a rare fossil, and has been hitherto found only at Braunsdorf and Freyberg in Saxony ; Rathhausberg iq Gastein in Salzburg ; and in Chili. Use. It is used as an ore of silver. Observations. 1. It is distinguished from the first subspecies by its inferior lustre, smallness of its crystals, fineness of the grain in the fracture, and its granular distinct concre tions. 2. Hausmann describes as a distinct species, a sulphuret of iron, with 4 per cent, of arsenic. He names it Arseni- kal kies, and considers it as synonymous with the Minera arsemcahs Jlavescens of Wallerius. It is found at Goslar in the Hartz. 3. Orpiment