A class of metallic meteorites containing between 6 and 17 per cent nickel by weight. Octahedrites contain two different forms of iron-nickel alloy, called kamacite and taenite. The intergrowth of crystals of the two types produces an octahedral form and a characteristic pattern, called the Widmanstätten figures, that shows up clearly on the surface of a slice of meteorite that has been polished and etched with dilute acid.