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
CategoryMetals and intermetallic alloys
Formula
(repeating unit)		γ-(Ni,Fe)
Strunz classification1.AE.10
Crystal systemIsometric
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFm3m
Identification
Colormetallic grayish to white
CleavageNone
FractureHackly fracture
TenacityMalleable, flexible
Mohs scale hardness5-5.5
Lustermetallic
Streaklight gray
DiaphaneityOpaque
Specific gravity7.8–8.22
Other characteristicsmagnetic, 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
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See also

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
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