Pyrite

Pyrite is commonly referred to as “fool’s gold.” Before the 1800’s, it was favored as a decorative stone, carved into rosettes, shoe buckles, rings, snuff boxes and other ornaments, and was extremely popular in England during the Victorian Age for its use in jewelry. Pyrite’s biggest use occurred during World War II when it was mined as a source of Sulfur for producing sulfuric acid used in industry. Although much lighter than gold, its brassy color and relatively high density misled many novice prospectors. Its name is derived from the Greek word pyr, meaning “fire,” because it emits sparks when struck by iron.

It is opaque and pale silvery yellow when fresh, turning darker and tarnishing with exposure to oxygen. Pyrite crystals may be cubic, octahedral, or twelve-sided “pyritohedra,” and are often striated. Pyrite can also be massive or granular, or form either flattened disks or nodules of radiating, elongate crystals. Pyrite occurs in hydrothermal veins, by segregation from magmas, in contact metamorphic rocks, and in sedimentary rocks, such as shale and coal, where it can either fill or replace fossils. Pyrite forms under reducing conditions, typically in environments with low oxygen levels, high sulfur content, and abundant iron.

It can form through both biological and abiotic processes. Pyrite is a widespread mineral and is found in various geological formations around the world.