A new calcium-aluminate from a refractory inclusion in the Leoville carbonaceous chondrite |
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| Authors: | Mireille Christophe Michel-Lévy Gero Kurat Franz Brandstätter |
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| Institution: | 1. Laboratoire de Minéralogie-Cristallographie, UniversitéPierre et Marie Curie, 4, Place Jussieu, F-75230, Paris France;2. Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Postfach 417, A-1014 Wien Austria |
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| Abstract: | The first meteoritic occurrence of CaAl4O7 is described from a Ca-Al-rich inclusion (CAI) in the Leoville carbonaceous chondrite. This CAI consists mainly of gehlenitic melilite, spinel, perovskite, and hibonite. CaAl4O7 is a minor component and occurs within melilite preferentially in portions rich in perovskite.The CAI is enveloped by a succession of three rims (from inside out): (a) hibonite+melilite+spinel+perovskite, (b) diopside, and (c) olivine.On the basis of mineral associations found and from the presence of moderately volatile elements (Fe and Cr) we conclude that the CaAl4O7-bearing CAI from Leoville is of residual nature. CaAl4O7 is apparently stable in the very Mg- and Si-poor environment of this CAI and is probably of igneous origin.The rims are interpreted as products of partial evaporation (rim (a)) and associated re-condensation (rims (b) and (c)). |
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