Krennerite

Gold telluride mineral
(repeating unit)AuTe2 to Au3AgTe8IMA symbolKnn[1]Strunz classification2.EA.15Crystal systemOrthorhombicCrystal classPyramidal (mm2)Space groupOrthorhombic
H-M symbol: (mm2)
Space group: Pma2IdentificationColorSilver white to brass yellow (tarnish?) – creamy white (polished section)Crystal habitMassive to crystalline with short striated prismatic crystalsCleavagePerfect on {001}FractureSubconchoidal – unevenTenacityBrittleMohs scale hardness2.5LusterHigh metallicStreakgreenish greyDiaphaneityopaqueSpecific gravity8.62Optical propertiesAnisotrophism strongRefractive indexOpaquePleochroismweakUltraviolet fluorescenceNoneReferences[2][3][4]

Krennerite is an orthorhombic gold telluride mineral which can contain variable amounts of silver in the structure. The formula is AuTe2, but specimen with gold substituted by up to 24% with silver have been found ([Au0.77Ag0.24]Te2).[2] 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 8.62 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).[4]

See also

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b "Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2021-03-03. Retrieved 2017-05-09.
  3. ^ Krennerite Mineral Data on Webmineral
  4. ^ a b Krennerite: Krennerite mineral information and data om Mindat
  • G. Tunnell and K. J. Murata, American Mineralogist 35, 359–384 (1950).
  • Structure of Krennerite retrieved 6-26-05
  • Euromineral retrieved 6-26-05
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