Widmanstätten pattern showing the two forms of nickel-iron minerals, kamacite and taenite
|Color||Iron black, steel gray|
|Crystal habit||Massive - uniformly indistinguishable crystals forming large masses|
|Crystal system||Isometric (4/m 3 2/m) Space Group: Fm3m|
|Fracture||Hackly - Jagged, torn surfaces, (e.g. fractured metals).|
|Mohs scale hardness||4|
|Other characteristics||non-radioactive, magnetic, non-fluorescent.|
Kamacite is an alloy of iron and nickel, which is found on earth only in meteorites. The proportion iron:nickel is between 90:10 to 95:5; small quantities of other elements, such as cobalt or carbon may also be present. The mineral has a metallic luster, is gray and has no clear cleavage although the structure is isometric-hexoctahedral. Its density is around 8 g/cm³ and its hardness is 4 on the Mohs scale. It is also sometimes called balkeneisen.
The name was coined in 1861 and is derived from the Greek kamask (lath or beam). It is a major constituent of iron meteorites (octahedrite and hexahedrite types). In the octahedrites it is found in bands interleaving with taenite forming Widmanstätten patterns. In hexahedrites, fine parallel lines called Neumann lines are often seen, which are evidence for structural deformation of adjacent kamacite plates due to shock from impacts.
At times kamacite can be found so closely intermixed with taenite that it is difficult to distinguish them visually, forming plessite. The largest documented kamacite crystal measured 92×54×23 centimetres (36.2×21.3×9.1 in).
- Mason B., 1962: Meteorites. J. Wiley & Sons, New York
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