Description: Hexahedrites consist primarily of kamacite, and they are named for the way that the crystal structure of kamacite is arranged according to the spatial form of a hexahedron. Pure kamacite forms cubic crystals with six equal sides at right angles to each other, and hexahedrites are actually large, cubic kamacite crystals. Upon etching, hexahedrites don't display any Widmanstätten figures, but they often exhibit fine, parallel lines called "Neumann lines" for their discoverer, Franz Ernst Neumann, who first studied them in 1848. These lines represent a shock-induced, structural deformation of the kamacite plates, and they suggest an impact history for the hexahedrite parent body, at least for the hexahedrites related to chemical group IIAB

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