A unique corundum and refractory metal-nugget bearing micrometeorite P117

1N. G. Rudraswami,1K. Reshma,1M. Shyam Prasad
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12783]
1National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa, India
Published by arrangement with John Wiley & Sons

Micrometeorites provide a large range of samples sourced from a wide variety of planetary materials, thereby providing a scope for expanding the known inventory of solar system materials. Here we report the micrometeorite AAS62-34-P117 having the assemblage of corundum, hibonite, unknown Al-rich phases, FeNi metal blebs, sulfide, and phosphate embedded in Al-rich silicate composition, and Pt-group element nuggets dispersed throughout the micrometeorite. Here, we report the presence of corundum in micrometeorites as a major refractory phase with sizes greater than ~10 μm. The Al-rich phases have Al2O3 ~50–70%, such high Al phases are not known from meteoritic components either in chondrules or refractory inclusions. In addition, the Ca content is extremely poor to relate it directly to known refractory inclusions, but is very high in Al. The presence of corundum in Al-rich phases indicates the micrometeorite to be early condensate from solar nebula that later got incorporated into Si-rich materials leading to a transformation that produced the unusual Al-rich and Ca-poor phases different from the average solar composition. The observed texture and mineralogy of the micrometeorite appears to have evolved in a nebular setting that has compositional reservoirs different from those of any known components of meteorites.

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