|Crystal class||Dihexagonal pyramidal (6mm) |
H-M symbol: (6mm)
|Jmol (3D)||Interactive image|
|Color||Brownish black, Orange brown, Reddish brown, Black.|
|Crystal habit||Radial clusters and colloform crusts and masses. Also as tabular crystals|
|Cleavage|| and |
|Fracture||Uneven - irregular|
|Mohs scale hardness||3.5-4|
|Luster||Resinous, brilliant submetallic on crystal faces|
|Specific gravity||4.09 measured, 4.10 calculated|
|Optical properties||Uniaxial (+)|
|Refractive index||n? = 2.356 n? = 2.378|
|Birefringence||? = 0.022|
|Other characteristics||Nonmagnetic, non-radioactive|
Wurtzite is a zinc iron sulfide mineral ((Zn,Fe)S) a less frequently encountered mineral form of sphalerite. The iron content is variable up to eight percent. It is trimorphous with matraite and sphalerite.
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 P?íbram, 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.
Its crystal structure is called the wurtzite crystal structure, to which it lends its name. This structure is a member of the hexagonal crystal system and consists of tetrahedrally coordinated zinc and sulfur atoms that are stacked in an ABABABABAB pattern.
The unit cell parameters of wurtzite are (-2H polytype):