Tetrahedrite is a

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

sulfosalt mineral with formula: . It is the antimony endmember of the continuous

solid solution A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solutio ...

series with

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

-bearing

tennantite Tennantite is a copper arsenic sulfosalt mineral with an ideal formula . Due to variable substitution of the copper by iron and zinc the formula is . It is gray-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahed ...

. 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 In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...

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 mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

of 3.5 to 4 and

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

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 th ...

veins and in some contact metamorphic deposits. It is a minor

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

of copper and associated metals. It was first described in 1845 for occurrences in

Freiberg, Saxony Freiberg () is a college town, university and former mining town in Saxony, Germany, with around 41,000 inhabitants. The city lies in the foreland of the Ore Mountains, in the Saxon urbanization axis, which runs along the northern edge of the ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

. 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 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.

Images

File:Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg, Tetrahedrite crystals with chalcopyrite and sphalerite from the Casapalca Mine, Peru (size: 8.2 × 6.4 × 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

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

Mineralogy

Applications

Images

See also

References

External links