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Published April 2014 | public
Journal Article

Allendeite (Sc_4Zr_3O_(12)) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite

Abstract

During a nanomineralogy investigation of the Allende meteorite with analytical scanning electron microscopy, two new minerals were discovered; both occur as micro- to nano-crystals in an ultrarefractory inclusion, ACM-1. They are allendeite, Sc_4Zr_3O_(12), a new Sc- and Zr-rich oxide; and hexamolybdenum (Mo,Ru,Fe,Ir,Os), a Mo-dominant alloy. Allendeite is trigonal, R3, ɑ = 9.396, c = 8.720, V = 666.7 Å^3, and Z = 3, with a calculated density of 4.84 g/cm^3 via the previously described structure and our observed chemistry. Hexamolybdenum is hexagonal, P6_3/mmc, ɑ = 2.7506, c = 4.4318 Å, V = 29.04 Å^3, and Z = 2, with a calculated density of 11.90 g/cm^3 via the known structure and our observed chemistry. Allendeite is named after the Allende meteorite. The name hexamolybdenum refers to the symmetry (primitive hexagonal) and composition (Mo-rich). The two minerals reflect conditions during early stages of the formation of the Solar System. Allendeite may have been an important ultrarefractory carrier phase linking Zr-,Sc-oxides to the more common Sc-,Zr-enriched pyroxenes in Ca-Al-rich inclusions. Hexamolybdenum is part of a continuum of high-temperature alloys in meteorites supplying a link between Os- and/or Ru-rich and Fe-rich meteoritic alloys. It may be a derivative of the former and a precursor of the latter.

Additional Information

© 2014 Mineralogical Society of America. Manuscript received July 12, 2013. Manuscript accepted November 11, 2013. Manuscript handled by Beda Hofmann. The Caltech GPS Analytical Facility is supported, in part, by NSF grants EAR- 0318518 and DMR-0080065. We also acknowledge NASA grant NNX12AH63G and NSF EAR-0947956. We thank the Smithsonian Institution for additional Allende samples and H.C. Connolly Jr. for bringing them to our attention. The review of A.M. Davis led to significant improvements in the manuscript.

Additional details

Created:
September 15, 2023
Modified:
October 23, 2023