Often referred to as "Fool's Gold", pyrite, or iron pyrite, is composed of Iron Sulfide. Its name is derived from the Greek word "pyr", or "fire". Pyrite is enjoyed by many because of its lustrous gold sheen, but sometimes appears in a yellow-gray or gray color. Sometimes oxidization of the pyrite will cause a brown or iridescent film to form on the face. Cubic structures are typical of Peruvian and Italian specimens, sometimes exhibiting a beautiful twinning penetration habit.