Taenite

Taenite (Fe,Ni) is a mineral found naturally on Earth mostly in iron meteorites. It is an alloy of iron and nickel, with nickel proportions of 20% up to 65%.

Taenite
Widmanstätten patterns of Kamacite and Taenite, from a meteorite currently in the Natural History Museum, London.
General
Category	Metals and intermetallic alloys
Formula (repeating unit)	γ-(Ni,Fe)
Strunz classification	1.AE.10
Crystal system	Isometric
Crystal class	Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group	Fm3m
Identification
Color	metallic grayish to white
Cleavage	None
Fracture	Hackly fracture
Tenacity	Malleable, flexible
Mohs scale hardness	5-5.5
Luster	metallic
Streak	light gray
Diaphaneity	Opaque
Specific gravity	7.8–8.22
Other characteristics	magnetic, not radioactive
References	[1][2]

Widmanstätten pattern showing the two forms of Nickel-Iron, Kamacite and Taenite, in an octahedrite meteorite

The name is derived from the Greek ταινία for "band, ribbon". Taenite is a major constituent of iron meteorites. In octahedrites it is found in bands interleaving with kamacite forming Widmanstätten patterns, whereas in ataxites it is the dominant constituent. In octahedrites a fine intermixture with kamacite can occur, which is called plessite.

Taenite is one of four known Fe-Ni meteorite minerals: The others are kamacite, tetrataenite, and antitaenite.

Properties

It is opaque with a metallic grayish to white color. The structure is isometric-hexoctahedral. Its density is around 8 g/cm³ and hardness is 5 to 5.5 on the Mohs scale. Taenite is magnetic, in contrast to antitaenite. The crystal lattice has the c≈a= 3.582±0.002 Å.[3] The Strunz classification is I/A.08-20, while the Dana classification is 1.1.11.2 . It is hexoctahedral (cubic) in structure.

Meteorite localities with taenite

• Campo del Cielo crater in Argentina.
• Henbury Meteorites Conservation Reserve in Australia.
• Canyon Diablo in Arizona.

See also

• Glossary of meteoritics
• List of minerals

References

1. http://rruff.geo.arizona.edu/doclib/hom/taenite.pdf Handbook of Mineralogy
2. http://webmineral.com/data/Taenite.shtml Webmineral data
3. Albertsen, F.; Knudsen, J. M.; Jensen, G. B. (Jun 1978). "Structure of taenite in two iron meteorites J.". Nature. 273 (5662): 453–454. Bibcode:1978Natur.273..453A. doi:10.1038/273453a0.

• Mason B., 1962: Meteorites. J. Wiley & Sons, New York