Hexahedrite is one of the main types of iron meteorite.
Hexahedrites have a nickel content of about
6% and are 92% composed of the nickel-iron mineral kamacite. Their name derives from
the cubic (hexahedral) cleavage of alpha-Fe,
Ni single crystals. Etching the polished surface of a hexahedrite reveals
no Widmanstätten pattern but
does often bring out a pattern known as Neumann
lines caused by the presence of systems of narrow, flat lamellae (plates)
in the kamacite. These lamellae are believed to have been shock-induced,
suggesting that the hexahedrite parent body experienced a major impact.
|A type IIA hexahedrite that fell
in Siberia in 1916