Open AccessMIL03346, the most oxidized Martian meteorite: A first look at spectroscopy, petrography, and mineral chemistry
Author(s) -
Dyar M. Darby,
Treiman Allan H.,
Pieters Carlé M.,
Hiroi Takahiro,
Lane Melissa D.,
O'Connor Vanessa
Publication year - 2005
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005je002426
Subject(s) - augite , meteorite , olivine , geology , martian , magnetite , mineral , astrobiology , geochemistry , plagioclase , mineralogy , petrography , chondrite , martian surface , mars exploration program , materials science , physics , paleontology , quartz , metallurgy
Meteorite MIL03346, recovered from Antarctica, is a nakhlite: an augite clinopyroxenite inferred to have originated from Mars' surface. MIL03346 contains ∼70% augite and 3% olivine in a fine‐grained mesostasis of basaltic glass, olivine, titanomagnetite, and pyrrhotite. Part of the olivine is altered to fine‐grained ferric clays and oxides: “iddingsite” as described in other nakhlites. Chemical compositions of augite and olivine (FeO/MnO and Fe/Mg) are nearly identical to those of other nakhlites and are consistent with a Martian origin. The augite contains significant Fe 3+ : ∼24% of total iron by Mössbauer spectroscopy and ∼13% by elemental analyses and crystal chemistry. This proportion of Fe 3+ in augite is consistent with high‐temperature equilibration near the QFM oxygen buffer. Thermal emission spectra are similar to those of other nakhlites. Visible to mid‐IR spectra of MIL03346 show the same absorption features as do other nakhlites but at distinctly lower reflectances (which likely represent Fe 3+ in augite and magnetite). MIL03346 appears to contain the most Fe 3+ of any Martian meteorite studied to date and to have come from the most oxidizing magmatic environment yet reported.