Geochemistry

Exotic Extraterrestrial Carbon

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Science  13 Feb 2004:
Vol. 303, Issue 5660, pp. 927
DOI: 10.1126/science.303.5660.927d

Graphite is a relatively rare mineral phase in meteorites. Some of the graphite found in some of the most primitive meteorites, the chondrites, originated from other stars.

Semenenko et al. describe seven unusual graphite-bearing xenoliths found within the Krymka chondrite. The graphite grains are different from other meteoritic graphite in their shape, size, mineral associations, metal and sulfide associations, and carbon isotopic abundances. The graphite probably formed by the compression and heating of an exotic organic compound during multiple shock events due to impacts on the Krymka parent body. The identity of the exotic organic species is still unclear, but these findings provide clues to the evolution of carbon-bearing materials that are ubiquitous components in everything from dusty disks around stars, to giant gas planet atmospheres, to terrestrial life. — LR

Geochim. Cosmochim. Acta 68, 455 (2004).

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