H chondrites are characterized by relatively high iron, nickel and sulfide contents (16-22% by weight). The sulfide is essentially iron sulfide (FeS), a mineral known as troilite. Because bronzite is the dominant form of pyroxene in these meteorites, H chondrites are also known as olivine-bronzite chondrites. H chondrites may be identified by the fact that their matrix displays abundant iron flakes and facets, which are often oxidized. Alteration grades for H chondrites range from 3 to 6. (There are no H1 or H2 chondrites). As described earlier, H6 chondrites have undergone significant thermal metamorphism, where H3 chondrites have not.
Most H chondrites are of the H5 petrologic type.