Wurtzite

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Wurtzite
Wurtzite mineral.jpg
General
Category Sulfide mineral
Formula
(repeating unit)
(Zn,Fe)S
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
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 [1][2][3]

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.[4] It is trimorphous with matraite and sphalerite.[1]

It occurs in hydrothermal deposits associated with sphalerite, pyrite, chalcopyrite, barite and marcasite. It also occurs in low-temperature clay-ironstone concretions.[1]

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.[2] 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.[1]

Wurtzite structure[edit]

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.[5]

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):[2]

  • a = b = 3.82 Å = 382 pm
  • c = 6.26 Å = 626 pm
  • V = 79.11 Å3
  • Z = 2

See also[edit]

References[edit]

  1. ^ a b c d Handbook of Mineralogy
  2. ^ a b c Wurtzite at Mindat.org
  3. ^ Wurtzite at Webmineral
  4. ^ Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged, pp. 226-228.
  5. ^ Wurtzite at Mindat.org

External links[edit]