[1] The concept behind this was developed in the 1970s, but it was quickly realized that igneous processes actually play a vital role in the formation of the so-called "nonmagmatic" meteorites.

While the parent body of the meteorites cools off, the metallic core crystallizes into meteoric iron, an iron-nickel alloy.

They share a number of similarities, the most easily recognizable is that they contain many silicate inclusions composed of olivine, pyroxene and feldspar.

Other iron meteorites can also contain silicate inclusions but with different mineralogy (IVA for example has tridymite and pyroxene).

[6] Two of those groups, the IAB and the IIICD meteorites are now classified as primitive achondrites.