The Burnwell, Kentucky, low iron oxide chondrite fall: Description, classification and origin

The Burnwell, Kentucky, meteorite fell as a single stone on 1990 September 4. The Burnwell meteorite has lower Fa in olivine (15.8 mol%), Fs in orthopyroxene (13.4 mol%), Co in kamacite (0.36 wt%), FeO from bulk chemical analysis (9.43 wt%), and Δ 17 O (0.51 ± 0.02%), and higher Fe, Ni, Co metal (19.75 wt% from bulk wet chemical analysis) than observed in H chondrites. The Burnwell meteorite plots on extensions of H‐L‐LL chondrite trends for each of these properties towards more reducing compositions than in H chondrites. Extensions of this trend have been previously suggested in the case of other low‐FeO chondrites or silicate inclusions in the HE iron Netschaëvo, but interpretation of the evidence in these meteorites is complicated by terrestrial weathering, chemical disequilibrium or reduction. In contrast, the Burn‐well meteorite is an equilibrated fall that exhibits no evidence for reduction. As such, it provides the first definitive evidence for extension of the H‐L‐LL ordinary chondrite trend beyond typical H values towards more reducing compositions.