Widmanstätten pattern showing the two forms of nickel-iron minerals, kamacite and taenite
General
Category
Meteorite mineral
Formula (repeating unit)
α-(Fe,Ni); Fe00.9Ni00.1
Strunz classification
1.AE.05
Crystal system
Isometric
Crystal class
Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group
Im3m
Identification
Formula mass
56.13 g/mol
Color
Iron black, steel gray
Crystal habit
Massive – uniformly indistinguishable crystals forming large masses
Cleavage
Indistinct
Fracture
Hackly – Jagged, torn surfaces, (e.g. fractured metals).
Mohs scale hardness
4
Luster
Metallic
Streak
Gray
Specific gravity
7.9
Other characteristics
Non-radioactive, magnetic, Non-fluorescent.
References
[1][2]
Kamacite is an alloy of iron and nickel, which is found on Earth only in meteorites. According to the International Mineralogical Association (IMA) it is considered a proper nickel-rich variety of the mineral native iron.[3][4] The proportion iron:nickel is between 90%:10% and 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 its crystal structure is isometric-hexoctahedral. Its density is about 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 root καμακ- "kamak" or κάμαξ "kamaks", meaning vine-pole.[5] 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 cm (36.2×21.3×9.1 in).[6]
^Mineralienatlas
^Kamacite Mineral Data
^"International Mineralogical Association (IMA), Commission on New Minerals, Nomenclature and Classification, IMA Official List of Minerals".
^Burke, E.A.J. (2006). "A mass discreditation of GQN minerals". The Canadian Mineralogist. 44 (6): 1557–1560. doi:10.2113/gscanmin.44.6.1557.
^"kamacite". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^P. C. Rickwood (1981). "The largest crystals" (PDF). American Mineralogist. 66: 885–907.
Kamacite is an alloy of iron and nickel, which is found on Earth only in meteorites. According to the International Mineralogical Association (IMA) it...
iron has a certain nickel concentration that leads to the exsolution of kamacite out of taenite while cooling. Octahedrites derive their name from the crystal...
hexahedrite iron meteorites in the kamacite phase, although they may appear also in octahedrites provided the kamacite phase is about 30 micrometres wide...
the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric iron makes up the bulk of iron meteorites but is...
meteorite massed about 3 milligrams (0.046 gr) and contained enstatite, kamacite, niningerite, silica, schreibersite, troilite, albite, and daubréelite...
with kamacite forming Widmanstätten patterns, whereas in ataxites it is the dominant constituent. In octahedrites a fine intermixture with kamacite can...
in Earth's outer and inner cores. Kamacite and taenite are naturally occurring alloys of iron and nickel. For kamacite, the alloy is usually in the proportion...
with total cooling times of 10 Myr or less—it will precipitate kamacite and grow kamacite plates along certain crystallographic planes in the taenite crystal...
alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Most iron meteorites originate from cores of planetesimals...
pentlandite, violarite, chromite, and millerite in peridotites; with kamacite, allabogdanite, schreibersite and graphite in meteorites. It was first...
meteoric iron. During cooling kamacite is exsolved from taenite. The lower the concentration of nickel, the more kamacite is formed. IIABs have some of...
examples are kamacite and taenite, which are found in iron meteorites; these species differ by the amount of Ni in the alloy; kamacite has less than...
with large amounts of schreibersite. The meteoric iron is composed of kamacite. Iron meteorites are designated with a Roman numeral and one or two letters...
octahedral inclusions in iron-containing meteorites. It typically accompanies kamacite, and more rarely schreibersite, cohenite or plessite. Cliftonite was first...
meteorite. They are composed almost exclusively of the nickel–iron alloy kamacite and are lower in nickel content than the octahedrites. The nickel concentration...
winonaites and chondrites. The IAB meteorites are composed of meteoric iron (kamacite and taenite) and silicate inclusions. Structurally they can be hexahedrites...
with minor amounts of plessite, troilite, and microscopic lamellae of kamacite. Ataxites are the most nickel-rich meteorites known; they usually contain...
meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Native iron is also rarely found in basalts that have formed...
primarily of the iron-nickel alloys: taenite (high nickel content) and kamacite (low nickel content). However, there are a few areas on earth where truly...
Type Stony-iron Subgroups A B C anomalous Composition Meteoric iron (kamacite, taenite & tetrataenite); silicates (mostly pyroxene & Ca-rich plagioclase);...
meteorite texture consisting of a fine-grained mixture of the minerals kamacite and taenite found in the octahedrite iron meteorites. It occurs in gaps...
seen to fall are iron meteorites composed of iron-nickel alloys, such as kamacite and/or taenite. Most iron meteorites are thought to come from the cores...
meteorites that fall to Earth turn out to be ferronickel, and take the form of kamacite and/or taenite.[citation needed] Ferronickel has a face-centred cubic crystal...
(fcc). Nickel iron mixtures tend to exsolve into a mixture of iron-rich kamacite and iron-poor taenite.: 27 Magnetochemistry Dunlop, David J.; Özdemir...
meteorite is an iron meteorite. It is structurally an ataxite with very rare kamacite lamella. The meteoric iron is a part of the lamella taenite. The total...
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