Traditionally a mineral that could be used for striking fire, but now a term commonly used to refer to various metallic sulfides. Iron pyrite (FeS₂), a hard, pale-yellow compound found in quartz and coal, was once a valuable source of sulfur. It is commonly called "Fools Gold" because of its similarity to gold.

Pyrite exists in isometric crystal forms such as cubes and pyritohedrons (pentagonal dodecahedrons). The original design of the Pyrite omnidirectional sound source called for a dodecahedral shape. The modification of the dodecahedral shape into an icosidodecahedral shape in the final design resulted in a better size to volume ratio, as well as reduced weight and improved ergonomic features. 

The Mineral and Gemstone Kingdom

Mineralogy Database

Pyrite can be found in Iceland!

Photograph: Hershel Friedman