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.