Amethyst cup with amethyst crystals. © 2010 Harold and Erica Van Pelt

Pyrite natural form 

Pyrite’s name comes from the Greek, pyrites lithos, “the stone which strikes fire.” The crystals form in the Isometric System; cubes, octahedrons, pyritohedrons and combinations of these and other forms. It also may be found in radiating disks, hair-like crystals, concretions and massive lumps in sulphide ore deposits.