Tetrahedrite is a
copper antimony sulfosalt
Sulfosalt minerals are sulfide minerals with the general formula , where
*A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium
*B usually represents semi-metal such as arsenic, antimony, bismuth, and rare ...
mineral with formula: . It is the antimony endmember of the continuous
solid solution series with
arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...
-bearing
tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, the antimony rich phase is more common. Other elements also substitute in the structure, most notably iron and zinc, along with less common silver, mercury and lead. Bismuth also substitutes for the antimony site and ''bismuthian tetrahedrite'' or ''annivite'' is a recognized variety. The related, silver dominant, mineral species
freibergite, although rare, is notable in that it can contain up to 18% silver.
Mineralogy
Tetrahedrite gets its name from the distinctive
tetrahedron shaped
cubic
Cubic may refer to:
Science and mathematics
* Cube (algebra), "cubic" measurement
* Cube, a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex
** Cubic crystal system, a crystal system w ...
crystals. The mineral usually occurs in massive form, it is a steel gray to black metallic mineral with
Mohs hardness
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.
The scale was introduced in 1812 by ...
of 3.5 to 4 and
specific gravity of 4.6 to 5.2.
Tetrahedrite occurs in low to moderate temperature
hydrothermal
Hydrothermal circulation in its most general sense is the circulation of hot water ( Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with t ...
veins and in some
contact metamorphic
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
deposits. It is a minor
ore
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 April ...
of copper and associated metals. It was first described in 1845 for occurrences in
Freiberg, Saxony,
Germany. Historically, it was an important ore of copper, the formula CuSbS corresponding with 57.5% of the metal; it was also worked as an ore of silver, of which element it sometimes contains as much as 30%.
Applications
The now-defunct company
Alphabet Energy announced plans to offer a
thermoelectric
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, wh ...
device based on tetrahedrite to turn heat into electricity. The company claimed that other thermoelectrics typically produce about 2.5 percent efficiency, while tetrahedrite could achieve 5 to 10 percent.
Other thermoelectrics are either scarce, expensive ($24–146/kg vs $4 for tetrahedrite) and/or toxic. Working with a natural material also reduces manufacturing costs.
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Images
File:Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg, Tetrahedrite crystals with chalcopyrite and sphalerite from the Casapalca Mine, Peru (size: 8.2 x 6.4 x 4.7 cm)
File:Tetrahedrite-27120.jpg, Tetrahedrite from Casapalca Mine, Casapalca, Huarochiri Province, Lima Department, Peru
File:Fluorite-Quartz-Rhodochrosite-ed10a.jpg, Rhodochrosite with fluorite, tetrahedrite and quartz; the tetrahedrite occurs as sharp, metallic crystals
File:Quartz-Tetrahedrite-denv08-50b.jpg, Tetrahedrite crystals to several inches on size in combination with quartz crystals
See also
* Bornite
* Cuprite
Cuprite is an oxide mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper.
Its dark crystals with red internal reflections are in the isometric system hexoctahedral class, appearing as cubic, octahedral, or dodecahedral forms, o ...
* List of minerals
References
External links
* Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., Wiley, {{ISBN, 0-471-80580-7
Mineral galleries
Webmineral data
Copper ores
Iron minerals
Sulfosalt minerals
Antimony minerals
Cubic minerals
Minerals in space group 217
Thermoelectricity