The enstatite chondrites

Fifteen enstatite chondrites have been recognized: Abee, Adhi Kot, Atlanta, Bethune, Blithfield, Daniel's Kuil, Hvittis, Indarch, Jajh deh Kot Lalu, Khairpur, Kota-Kota, Pillistfer, St. Mark's, Saint-Sauveur and Ufana. Their essential minerals are enstatite and/or clinoenstatite (40-60%), kamacite (20-28%), troilite (7-15%), and sometimes plagioclase (5-10%). A considerable number of accessory minerals, some of them unique to this group, have been recorded. Chondritic structure is seldom well developed, and some of these meteorites appear to be completely recrystallized and lack chondrules entirely. Their bulk chemical composition is similar throughout, the principal variable being total Fe, which ranges from 20.71 in Blithfield to 35.02 in Saint-Sauveur. Some trace elements, however, show remarkable variation between the individual meteorites. Geochemically the enstatite chondrites are characterized by a high degree of reduction, Fe, Ni, Co, Cr, Mn and Ti being present in metal and/or sulfide phases, and some Si being in solid solution in the nickel-iron.