Sphalerite Specimen

Description

Sphalerite Pitcher Oklahoma (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula (Zn,Fe)S.^[5] It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits. It is found in association with galena, chalcopyrite, pyrite (and other sulfides), calcite, dolomite, quartz, rhodochrosite, and fluorite.^[6]

German geologist Ernst Friedrich Glocker discovered sphalerite in 1847, naming it based on the Greek word sphaleros, meaning “deceiving”, due to the difficulty of identifying the mineral.^[7]

In addition to zinc, sphalerite is an ore of cadmium, gallium, germanium, and indium. Miners have been known to refer to sphalerite as zinc blende, black-jack, and ruby blende.^[8] Marmatite is an opaque black variety with a high iron content.^[9]The crystal structure of sphalerite

Sphalerite crystallizes in the face-centered cubic zincblende crystal structure,^[10] which named after the mineral. This structure is a member of the hextetrahedral crystal class (space group F43m). In the crystal structure, both the sulfur and the zinc or iron ions occupy the points of a face-centered cubic lattice, with the two lattices displaced from each other such that the zinc and iron are tetrahedrally coordinated to the sulfur ions, and vice versa.^[11] Minerals similar to sphalerite include those in the sphalerite group, consisting of sphalerite, colaradoite, hawleyite, metacinnabar, stilleite and tiemannite.^[12] The structure is closely related to the structure of diamond.^[10] The hexagonal polymorph of sphalerite is wurtzite, and the trigonal polymorph is matraite.^[12] Wurtzite is the higher temperature polymorph, stable at temperatures above 1,020 °C (1,870 °F).^[13] The lattice constant for zinc sulfide in the zinc blende crystal structure is 0.541 nm.^[14] Sphalerite has been found as a pseudomorph, taking the crystal structure of galena, tetrahedrite, barite and calcite.^[13][15] Sphalerite can have Spinel Law twins, where the twin axis is [111].

The chemical formula of sphalerite is (Zn,Fe)S; the iron content generally increases with increasing formation temperature and can reach up to 40%.^[6] The material can be considered a ternary compound between the binary endpoints ZnS and FeS with composition Zn_xFe_(1-x)S, where x can range from 1 (pure ZnS) to 0.6.