Krennerite

Krennerite
Krennerite from the Cresson Mine, Cripple Creek, Colorado (about 5 mm).
General
Category	Telluride mineral
Formula (repeating unit)	AuTe2
Strunz classification	2.EA.15
Crystal system	Orthorhombic
Crystal class	Pyramidal (mm2) H-M symbol: (mm2)
Space group	Pma2
Identification
Formula mass	453.2 g/mol
Color	White to blackish yellow
Crystal habit	Massive to crystalline
Cleavage	Perfect
Fracture	Conchoidal
Mohs scale hardness	2.5
Luster	Metallic
Streak	greenish grey
Diaphaneity	opaque
Density	8.53
Optical properties	Anisotrophic
Pleochroism	weak
Ultraviolet fluorescence	None
References

Krennerite is an orthorhombic gold telluride mineral which can contain a relatively small amount of silver in the structure. The formula is AuTe₂ varying to (Au_0.8,Ag_0.2)Te₂. Both of the chemically similar gold-silver tellurides, calaverite and sylvanite, are in the monoclinic crystal system, whereas krennerite is orthorhombic.

The color varies from silver-white to brass-yellow. It has a specific gravity of 8.53 and a hardness of 2.5. It occurs in high temperature, hydrothermal environments.

Krennerite was discovered in 1878 near the village of Săcărâmb, Romania, and first described by the Hungarian mineralogist Joseph Krenner (1839–1920).

See also

• List of minerals
• List of minerals named after people

References

• G. Tunnell and K. J. Murata, American Mineralogist 35, 359-384 (1950).
• Structure of Krennerite retrieved 6-26-05
• Euromineral retrieved 6-26-05

Krennerite in a quartz vein, Cresson Mine, Cripple Creek, Colorado. Specimen size 3.0 x 2.7 x 2.5 cm. See infobox for detail photo.