Cubes of pyrite from Ampliación a Victoria Mine in Spain. Pyrite, or iron pyrite, is nicknamed "fool's gold" due to its metallic luster and brass-yellow hue. The most common of the sulfide minerals, pyrite has been used in firearms, the production of sulfur dioxide, radio receivers, and jewellery. The name "pyrite" is derived from the Greek πυρίτης (puritēs), “of fire” or "in fire”, and ancient Romans applied the name to several types of stone that would create sparks when struck against steel.Photo credit: Noodle snacks