Ataxite is a rare variety of iron meteorite (designated type D) made almost entirely of taenite, a solid solution of iron and 27% to 65% nickel; the Greek name means "without structure" and refers to the lack of a visible Widmanstätten pattern (spindles of kamacite being visible only microscopically). Strangely enough, the largest meteorite known, the Hoba meteorite, belongs to this rare structural class.

Compare with octahedrite and hexahedrite.