Wurtzite
Wurtzite is a zinc and iron sulfide mineral with the chemical formula (Zn,Fe)S, a less frequently encountered structural polymorph form of sphalerite. The iron content is variable up to eight percent. It is trimorphous with matraite and sphalerite.
| Wurtzite | |
|---|---|
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | (Zn,Fe)S |
| IMA symbol | Wur |
| Strunz classification | 2.CB.45 |
| Dana classification | 02.08.07.01 |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal pyramidal (6mm) H-M symbol: (6mm) |
| Space group | P63mc |
| Structure | |
| Jmol (3D) | Interactive image |
| Identification | |
| Color | Brownish black, orange brown, reddish brown, black |
| Crystal habit | Radial clusters and colloform crusts and masses. Also as tabular crystals |
| Cleavage | [1120] and [0001] |
| Fracture | Uneven – irregular |
| Mohs scale hardness | 3.5–4 |
| Luster | Resinous, brilliant submetallic on crystal faces |
| Streak | light brown |
| Diaphaneity | Translucent |
| Specific gravity | 4.09 measured, 4.10 calculated |
| Optical properties | Uniaxial (+) |
| Refractive index | nω = 2.356 nε = 2.378 |
| Birefringence | δ = 0.022 |
| Other characteristics | Nonmagnetic, non-radioactive |
| References | |
It occurs in hydrothermal deposits associated with sphalerite, pyrite, chalcopyrite, barite and marcasite. It also occurs in low-temperature clay-ironstone concretions.
It was first described in 1861 for an occurrence in the San José Mine, Oruro City, Cercado Province, Oruro Department, Bolivia, and named for French chemist Charles-Adolphe Wurtz. It has widespread distribution. In Europe it is reported from Příbram, Czech Republic; Hesse, Germany; and Liskeard, Cornwall, England. In the US it is reported from Litchfield County, Connecticut; Butte, Silver Bow County, Montana; at Frisco, Beaver County, Utah; and from the Joplin district, Jasper County, Missouri.