Wurtzite

This article is about the mineral. For the crystal structure, see Wurtzite (crystal structure).

Not to be confused with Wüstite, a mineral form of mostly iron(II) oxide.

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.^[5] It is trimorphous with matraite and sphalerite.^[2]

Wurtzite
General
Category	Sulfide mineral
Formula	(Zn,Fe)S
IMA symbol	Wur[1]
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	[2][3][4]

It occurs in hydrothermal deposits associated with sphalerite, pyrite, chalcopyrite, barite and marcasite. It also occurs in low-temperature clay-ironstone concretions.^[2]

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.^[3] 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.^[2]

Structure

Wurtzite unit cell. The grey balls represent metal atoms, and yellow balls represent sulfur or selenium atoms.

The wurtzite group includes cadmoselite (CdSe), greenockite (CdS), mátraite (ZnS), and rambergite (MnS), in addition to wurtzite.^[6]

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):^[7]

• a = b = 3.81 Å = 381 pm
• c = 6.23 Å = 623 pm
• V = 78.41 ų
• Z = 2

See also

• Wurtzite crystal structure