Formula: FeNi
Alloy, iron-nickel group
Specific gravity: 8.28 calculated
Hardness: 3½
Streak: Grey
Colour: Grey-white, silver-white
Magnetism: Strongly magnetic
Common impurities: Co,Cu,P

Hydrothermal environments very rare

Tetrataenite is common in iron meteorites, but very rare in terrestrial rocks (Mindat).

In Meteorites

Tetrataenite occurs as exsolution rims and grains in slowly cooled meteorites, by the ordering of iron and nickel atoms in taenite. It is most abundant in mesosiderites and chondrites. Associated minerals include kamacite, troilite and taenite (AM 65.624-630, HOM).

In Terrestrial Rocks

Terrestrial tetrataenite has been found in an ophiolite-hosted nickel-bearing magnetite body from the Indo-Myanmar ranges, northeast India. Although the mineral assemblage surrounding it is very similar to that found in the meteorites, the postulated cooling regimes cannot be similar. Terrestrial tetrataenite is formed as a consequence of hydrothermal alteration of ferromagnesian minerals of the olivine and pyroxene groups. Iron and nickel were released from the silicates and precipitated in the form of an iron-nickel alloy at low temperature in extremely reducing conditions with a lack of sulphur. A low temperature hydrothermal origin of tetrataenite is suggested (AM 100.209-214). Associated minerals include chamosite, magnetite, chromite and chromium-aluminium spinel (HOM).


The type locality is the Estherville meteorite, Emmet county, Iowa, USA, where tetrataenite occurs as 10-50 micron sized grains (Mindat).

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