Note on type 7 Chondrites. There is no firm agreement among meteorite researchers on the definition of type 7 chondrites. Many meteorites previously described as type 7 are either type 6 or are impact melts . Impact melting is not considered a proper basis for type 7 classification. Future research is expected to clear up this issue.
H indicates high metallic iron and L indicates low metallic iron.
Brecciated meteorites with clasts of more than one type of alteration are designated with the range of alteration present in the meteorite. The letter designation refers to the iron content for the meteorite as a whole. E.g., Zag bears the designation H3-6 . Principle minerals are bronzite , olivine , and minor oligoclase . These rare meteorites contain elemental carbon , a basic building block for life.