They are composed almost exclusively of the nickel–iron alloy kamacite and are lower in nickel content than the octahedrites.

[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] Concentrations of trace elements (germanium, gallium and iridium) are used to separate the iron meteorites into chemical classes, which correspond to separate asteroid parent bodies.