Pyrite (from the Greek word "feast" fire) is a sulfuric or iron pyrite, the most common mineral from the sulphide group. This mineral is of great technical importance, being at the present time the main material for the production of sulfuric acid.

Pyrite from the Greek word feast fire is a sulfuric or iron pyrite, the most common mineral from the sulphide group

Fig.Pyrite (size 18 cm, Berezovsky mine near Yekaterinburg (Ural, Russia))

Mineral pyrite is found to be yellowish or greenish-gray in color with metallic sheen, in the forms of a regular system, usually in the form of solid masses consisting of very small crystals, and sometimes also in the form of perfectly developed cubes, octahedra, pyramidal cubes and other combinations thereof; there are often also twins in the form of mutually sprouted cubes, etc. (see Fig.). The specific gravity of pyrite varies from 4,83 to 5,2 g/cm3; hardness 6-6,5, the fracture is uneven or conchoidal.

Pure pyrite has the chemical formula FeS2 and contains 53,33% sulfur and 46,68% iron. When a metallic object is struck from pyrite, sparks are chiseled - probably this property also reflects the name of the mineral. Dimensions of pyrite crystals often reach several centimeters and are a good collection material.

Pyrite is found both in volcanic rocks and in sedimentary rocks. Pyrite of the last rocks differs in that it is easier to weather and oxidize in air, passing into sulfuric iron. Even more easily weathered and oxidized its special variety, marcasite, which has the same composition, but crystallizes in a rhombic system and very often occurs in the form of a variety of twins, tees, and so on. (crested pyrites, hepatic pyrite, etc.). Marcasite has a specific gravity of 4,65-4,88 g/cm3, the same hardness, colored lighter than pyrite, usually greenish gray, and occurs in sedimentary rocks, very often in bituminous shales and Carboniferous strata. Pyrites are usually admixed with pyrite Fe7S8 (39,5% sulfur), copper FeCuS2, and almost always arsenic FeSAs.

Pyrite has the most important deposits in southern Spain, Portugal, southern France, Sweden, Norway and the USA (Massachusetts, New York, Virginia, Georgia), in Russia at Ural and in the Altai, in Transcaucasia. On the Berezovskoye gold deposit in the Urals, there are druses of pyrite crystals weighing up to 32 kg.