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Published January 2014 | public
Journal Article

Monipite, MoNiP, a new phosphide mineral in a Ca-Al-rich inclusion from the Allende meteorite

Abstract

Monipite (IMA 2007-033), MoNiP, is a new phosphide mineral that occurs as one 1 × 2 μm crystal in a Type B1 Ca-Al-rich inclusion (CAI) ACM-2 from the Allende CV3 carbonaceous chondrite. It has an empirical formula of (Mo_(0.84)Fe_(0.06)Co_(0.04)Rh_(0.03))(Ni_(0.89)Ru_(0.09))P, and a P6̄ 2m Fe_2P type structure with a = 5.861, c = 3.704 Å, V = 110.19 Å3, and Z = 3. The calculated density using our measured composition is 8.27 g/cm^3, making monipite the densest known mineral phosphide. Monipite probably either crystallized from an immiscible P-rich melt that had exsolved from an Fe-Ni-enriched alloy melt that formed during melting of the host CAI or it exsolved from a solidified alloy. Most of the original phosphide in the type occurrence was later altered to apatite and Mo-oxides, leaving only a small residual grain. Monipite occurs within an opaque assemblage included in melilite that contains kamiokite (Fe_2Mo_3O_8), tugarinovite (MoO_2), and a Nb-rich oxide [(Nb,V,Fe)O_2], none of which has previously been reported in meteorites, together with apatite, awaruite (Ni_2Fe), and vanadian magnetite.

Additional Information

© 2014 Mineralogical Society of America. Manuscript received February 21, 2013. Manuscript accepted August 31, 2013. Manuscript handled by Oliver Tschauner. The Caltech GPS Analytical Facility is supported, in part, by NSF grants NSF EAR-0318518 and DMR-0080065. We also acknowledge NASA grant NNG04GG14G and NSF grant EAR-0947956. We thank Alan Rubin, an anonymous reviewer, and associate editor Oliver Tschauner for helpful reviews.

Additional details

Created:
August 22, 2023
Modified:
October 25, 2023