Arsenopyrite

arsenopyrite (är'sĭnōpī`rīt, ärsĕn`ō–) or mispickel (mĭs`pĭkəl), silver-white to steel-gray mineral with the metallic luster characteristic of a pyrite. It is a sulfarsenide of iron, FeAsS, crystallizing in the orthorhombic system and occurring also in massive form. It is widely distributed and is an important source of arsenic. Often it is found associated with other minerals and ores of lead and tin. Saxony, Sweden, Cornwall, and various parts of the United States have important deposits.

---

arsenopyrite [‚ärs·ən·ō′pī‚rīt]

(mineralogy)

FeAsS A white to steel-gray mineral crystallizing in the monoclinic system with pseudo-orthorhombic symmetry because of twinning; occurs in crystalline rock and is the principal ore of arsenic. Also known as mispickel.

---

Arsenopyrite 

(or mispickel), a mineral belonging to the group of the sulfur-arsenic compounds of iron. The chemical composition is FeAsS. It usually contains admixtures of an isomorphic nature (cobalt, nickel). It forms the series arsenopyrite (up to 3 percent Co)-danaite (up to 12 percent Co)-glaucodot (more than 12 percent Co). The system is mono-clinic (by the latest data, triclinic); it forms pseudorhombic, prismatic, columnar, and needlelike crystals, starlike growths, and columnar and grainy aggregates. Arsenopyrite has a metallic luster, and its color is tin-white. Its hardness on the mineralogical scale is 5.5–6. The density is 5,9000–6,200 kg/m³. When struck, arsenopyrite gives off a sharp odor of garlic. Arsenopyrite is encountered in ore veins together with the sulfides of lead, zinc, and bismuth, as well as with tungsten, cassiterite, gold nuggets, and others. Formation within a wide temperature range is characteristic of arsenopyrite. (It is found in pegmatites and hydrothermal deposits.) Upon being subjected to weathering and oxidation of the surface of the earth, arsenopyrite is transformed into scorodite and other hydrated arsenates of iron. Arsenopyrite is the principal raw material for the extraction of arsenic, and less frequently of cobalt and nickel.