A type IIA hexahedrite that fell in Siberia in 1916.
A 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.