They are relatively rare, and can be distinguished by the presence of large olivine crystal inclusions in the ferro-nickel matrix.

These crystals represent mantle and core material from differentiated planetesimals, which were destroyed by violent collisions during the early formation of the Solar System.

Minor constituents are schreibersite, troilite, chromite, pyroxenes, and phosphates (whitlockite, stanfieldite, farringtonite, and merrillite).

This hypothesis is supported by isotopic analysis indicating admixture of material from multiple planetesimals.

Chladni in the 1790s to demonstrate the reality of meteorite falls on the Earth, which most scientists at his time considered as fairytales.