Arsenopyrite, or Mispickel, a silvery-white to grayish mineral with grayish-black streaks and a metallic luster. The mineral is generally found in the form of wedge-shaped crystals. Arsenopyrite is one of the most important ores of arsenic and often is an ore of gold as well. When crushed or heated, the ore gives off an odor like that of garlic.
Chemical formula: FeAsS. Specific gravity: 5.9--6.2. Hardness: 5.5--6.