Pyrite (from the Greek "pyr" which means fire) is an iron disulfide with a yellow-gold color (due to sulfur) and opaque metallic lustre. It is a well-known mineral common for the extraction of iron and sulfur. Because of the color it has often been confused with gold and for this reason it is nicknamed "gold of fools". It crystallizes in the monometric system; occurs typically as cubic pentagon-dodecahedral crystals with alternating faces longitudinally striated. Less frequently octahedral, it often presents as massive, granular, and sometimes reniform, discoid or globular.
It is found in all types of rocks but more commonly in igneous rocks of hydrothermal origin as an accessory component and in metamorphic and sedimentary rocks as a mineral of secondary origin. It can also be found as a replacement mineral in many fossils, sedimented in an anoxic environment.
It is common in many deposits; beautiful and large crystals occur in Italy, in Traversella, on the island of Elba, in Tuscany, in Liguria, in the Piedmont Alps, in Val Malenco, in Val Sesia, in Anzasca Valley. It is abundant in Spain, Portugal, Japan and North America.
In ancient times it was used to make flintlocks, because when struck, it gives off sparks; today it is widely used for the production of various ornaments, taking advantage of the beautiful shine that it can acquire by polishing.