Mineralogy of a Unique Graphite-Containing Fragment in the Krymka Chondrite (LL3)

V. P. Semenenko1, 2 and A. L. Girich1
1 Institute of Geochemistry, Mineralogy and Ore Formation National Academy of Sciences of Ukraine, Paladin-34, Kiev-142, Ukraine
2 Museum National d'Histoire Naturelle, Paris, France

Abstract: The Krymka chondrite contains an exotic graphite-bearing fragment that appears to be of a new type of material added to unequilibrated LL-chondrite during agglomeration on the surface of the parent body. The fine-granular texture without chondrules, two morphological groups of graphite crystals which differ in size and occurence, high content of troilite (11.3 vol.%), the high Ni (55.5–66.6 wt.%) and Co (1.59–2.87 wt.%) contents of the taenite and absence of kamacite, the presence of F-apatite, which is rare for meteorites but common for lunar and terrestrial igneous rocks, are the main features of the fragment.

The mineralogy and texture indicate: (1) the fragment probably formed by crystallization from a highly reduced silicate melt, which had been enriched in carbon; 2) the subsequent metal sulphidization lowered its abundance and resulted in the formation of troilite and the compositional features of the residual metal; (3) terrestrial weathering of an exotic fragment and the host part of the chondrite produced iron hydroxides, pentlandite and quite possibly magnetite.

Keywords: chondrite • fragment • graphite • filiform crystals

Mineralogical Magazine; September 1995 v. 59; no. 396; p. 443-454; DOI: 10.1180/minmag.1995.059.396.06
© 1995, The Mineralogical Society
Mineralogical Society (www.minersoc.org)