Krennerite
Encyclopedia
Krennerite is an orthorhombic gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 telluride mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 which can contain a relatively small amount of silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

 in the structure. The formula is AuTe2 varying to (Au0.8,Ag0.2)Te2. Both of the chemically similar gold-silver tellurides, calaverite
Calaverite
Calaverite, or gold telluride, is an uncommon telluride of gold, a metallic mineral with the chemical formula AuTe2, with approximately 3% of the gold replaced by silver. It was first discovered in Calaveras County, California in 1861, and was named for the county in 1868.The mineral often has a...

 and sylvanite
Sylvanite
Sylvanite or silver gold telluride, Te2, is the most common telluride of gold.-Properties:The gold:silver ratio varies from 3:1 to 1:1. It is a metallic mineral with a color that ranges from a steely gray to almost white. It is closely related to calaverite, which is more purely gold telluride with...

 are in the monoclinic crystal system, whereas krennerite is orthorhombic.

The color varies from silver-white to brass-yellow. It has a specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of 8.53 and a hardness of 2.5. It occurs in high temperature hydrothermal environments.

Krennerite was discovered in 1877 in Sacaramb, Romania, and first described by the Hungarian
Kingdom of Hungary
The Kingdom of Hungary comprised present-day Hungary, Slovakia and Croatia , Transylvania , Carpatho Ruthenia , Vojvodina , Burgenland , and other smaller territories surrounding present-day Hungary's borders...

 mineralogist Joseph Krenner (1839–1920).
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