Pyrite is also known as “fools gold” because it was frequently mistaken for gold. Pyrite and gold often form together and when this occurs, pyrite can have trace amounts of gold. Pyrite is an iron sulfide (FeS2) and has a hardness of 6-6.5 on the Mogs hardness scale.
Pyrite comes from the Greek word “pyr” meaning “fire” because it would create sparks when struck with a hard swipe against metal. Pyrite occurs as well-formed crystals of cubes, octahedron and pyritohedron. The two best locations for really well crystallized and brilliant pyrite are Navajum, Spain, and the mines in Peru.
Navajun, Spain, produces unbelievably perfect cubes in marl (marlstone) matrix. It is soft calcium carbonate and to maintain its integrity should not be washed with water.