Hexahedrite

Hexahedrite
— Structural class —
Neumann bands in the Sikhote-Alin meteorite
Compositional typeIron
CompositionKamacite
A phase diagram showing the link between structural and chemical classification. Hexahedrites contain mostly kamacite because their chemistry only allows kamacite as a stable phase.

Hexahedrites are a structural class of iron meteorite. They are composed almost exclusively of the nickeliron alloy kamacite and are lower in nickel content than the octahedrites.[1] The nickel concentration in hexahedrites is always below 5.8% and only rarely below 5.3%.[2]

The name comes from the cubic (i.e. hexahedron) structure of the kamacite crystal. After etching, hexahedrites do not display a Widmanstätten pattern, but they often do show Neumann lines: parallel lines that cross each other at various angles, and are indicative of impact shock on the parent body. These lines are named after politician Johann Georg Neumann [de] who discovered them in 1848.[3]

  1. ^ Buchwald, Vagn F. (1975). Handbook of Iron Meteorites. Vol. 1–3. University of California Press. OCLC 928839971.
  2. ^ Wasson, J.T. (1985). Meteorites: Their Record of Early Solar-System History. W. H. Freeman. ISBN 9780716717003.
  3. ^ Burke, J.G. (1991) [1986]. "Note 63. Schreibers (1820), 70–72". Cosmic Debris: Meteorites in History. University of California Press. p. 339. ISBN 9780520073968.

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