Wurtzite

(mineralogy) (Zn,Fe)S A brownish-black hexagonal mineral consisting of zinc sulfide and occurring in hemimorphic pyramidal crystals, or in radiating needles and bundles.

A mineral with composition ZnS (zinc sulfide). It exists most commonly in fibrous or columnar aggregates and banded crusts with resinous luster and brownish-black color. Hardness is 3½ on Mohs scale and its specific gravity 4.0. Zinc sulfide is dimorphous, crystallizing as both the high-temperature form wurtzite, α-ZnS, and the low-temperature form sphalerite, β-ZnS. Wurtzite is the rarer and at room temperature the less stable form and, unlike sphalerite, is rarely mined as an ore of zinc. Wurtzite usually contains iron and cadmium, and a complete solid solution series extends to greenockite, CdS. See also Greenockite; Sphalerite.

Wurtzite
General
Category	mineral
Chemical formula	(Zn,Fe)S
Identification
Color	Brownish black, Orange brown, Reddish brown, Black.
Crystal habit	Colloform - Forming from a gel or colloidal mass
Crystal system	Hexagonal P63mc
Cleavage	[1010] Good, [0001] Good
Fracture	Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Mohs Scale hardness	3.5-4
Luster	Adamantine - Resinous
Streak	light brown
Specific gravity	3.98 - 4.08, Average = 4.03
Refractive index	w=2.356, e=2.378, bire=0.0220
Other characteristics	Nonmagnetic, non-radioactive

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

Wurtzite unit cell. The blue balls represent sulfur atoms, and each yellow ball represents either a zinc atom or an iron atom.

Wurtzite is a zinc iron sulfide mineral ((Zn,Fe)S) a less frequently encountered mineral form of sphalerite.

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 ABABAB pattern.

The unit cell parameters of wurtzite are

• a = b = 3.81 Å = 381 pm
• c = 6.23 Å = 623 pm

It occurs in hydrothermal deposits associated with sphalerite, pyrite, chalcopyrite, barite and marcasite.

It was first described for an occurrence in Príbram, Czech Republic in 1861 and named for French chemist Charles-Adolphe Wurtz.

References

• Mineral Handbook
• Webmineral
• Mindat

External links

The Mineral Wurtzite

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