Sylvanite

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Sylvanite
Sylvanite ((Au,Ag)2Te4), Cripple Creek Diatreme.jpg
Sylvanite from the Cripple Creek mining district
General
Category Telluride mineral
Formula
(repeating unit)
(Ag,Au)Te2
Strunz classification 2.EA.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P2/c
Identification
Formula mass 429.89 g/mol
Color Silver-grey, Silver-white
Crystal habit Massive to Crystalline
Cleavage Perfect on the {010}
Fracture Uneven
Tenacity Brittle
Mohs scale hardness 1.5-2
Luster Metallic
Streak steel grey
Diaphaneity opaque
Specific gravity 8.2
Density 8.1
Optical properties Anisotropic
Pleochroism None
Ultraviolet fluorescence None
References [1][2][3]

Sylvanite or silver gold telluride, (Ag,Au)Te2, is the most common telluride of gold.

Properties[edit]

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 3% silver. Sylvanite crystallizes in the monoclinic 2/m system. Crystals are rare and it is usually bladed or granular. It is very soft with a hardness of 1.5 - 2. It has a high relative density of 8 - 8.2. Sylvanite is photosensitive and can accumulate a dark tarnish if it is exposed to bright light for too long.

Occurrence[edit]

Sylvanite is found in Transylvania, from which its name is partially derived.[4] It is also found and mined in Australia in the East Kalgoorlie district. In Canada it is found in the Kirkland Lake Gold District, Ontario and the Rouyn District, Quebec. In the United States it occurs in California and in Colorado where it was mined as part of the Cripple Creek ore deposit. Sylvanite is associated with native gold, quartz, fluorite, rhodochrosite, pyrite, acanthite, nagyagite, calaverite, krennerite, and other rare telluride minerals. It is found most commonly in low temperature hydrothermal vein deposits.

Use[edit]

Sylvanite represents a minor ore of gold and tellurium. Sylvanium, an obsolete term for tellurium, derived its name from sylvanite.[5]

References[edit]

  1. ^ Sylvanite: Sylvanite mineral information and data
  2. ^ Sylvanite Mineral Data
  3. ^ SYLVANITE (Silver Gold Telluride)
  4. ^ Jolyon, Ralph. "Sylvanite". mindat.org. Retrieved 18 January 2013. 
  5. ^ Klein, Cornelis (1985), Hurlbut, Cornelius S., ed., Manual of Mineralogy: (after James D. Dana) (20ᵗʰ ed.), Albuquerque, US-NM: Wiley, p. 290, ISBN 0-471-80580-7, retrieved 2017-06-28 

External links[edit]

Wikisource-logo.svg Chisholm, Hugh, ed. (1911). "Sylvanite". Encyclopædia Britannica (11th ed.). Cambridge University Press.