Petrography and mineralogy of calcium-, aluminum-rich inclusions in an unequilibrated carbonaceous chondrite Y 81020 (CO3.05)

Abstract

Petrographic and quantitative analyses of more than 70 refractory inclusions found in the studied thin section of Yamato 81020 (CO3.05) showed diverse objects that can be grouped into five distinct types based on morphology and mineralogy. Mineralogical, textural similarities to the pristine carbonaceous vigarano (3.1-3.4) types of Efremovka, Vigarano were observed despite their smaller size (~100 micron diameter). Wark-Lovering rims were found predominantly in melilite-rich calcium, aluminum-rich inclusions. Comparison of mineralogy, morphology at macro and micro scale of Y 81020 with ALH A77307 and other carbonaceous chondrites is suggestive of the unaltered characteristics of the refractory inclusions in agreement with previous studies.