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AN H4–6 CHONDRITE: MOTTA DI CONTI
Author(s) -
LeviDonati G.R.,
Maras A.,
Sighinolfi G.P.
Publication year - 1980
Publication title -
meteoritics
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0026-1114
DOI - 10.1111/j.1945-5100.1980.tb00525.x
Subject(s) - chondrite , chondrule , meteorite , petrography , geology , geochemistry , kamacite , pyroxene , electron microprobe , olivine , mineralogy , parent body , astrobiology , physics
The mineralogical and chemical compositions of meteorites from the Motta di Conti, Vercelli, Italy, shower (February 29, 1868) have been determined. Microprobe analyses, of olivine (Fa 19,6 ) and orthopyroxene (Fs 17,8 ), as well as the bulk chemical composition, particularly the ratios of SiO 2 /MgO (1.50), Fe°/Ni° (11.03), Fe total /SiO 2 (0.81), Fe°/Fe total (0.70) and the content of Fe total (28.60%) classify the meteorite as an H‐group chondrite. The percentage of total metallic nickel‐iron (22.06%) is somewhat higher than the average in H‐group chondrites. The texture of our stone shows evidence of metamorphism. The integration between matrix and chondrules is advanced and may suggest a high petrographic grade, but the identification of several microscopic features (e.g. small grains of monoclinic twinned pyroxene, FeNi‐FeS intergrowths, globules and mosaic) leads to the conclusion that a variety of petrographic types (4–6) are present. Metamorphic equilibration in chondrites is discussed and a preliminary hypothesis for H4–6 chondrites is suggested.