Characterization of carbonaceous matter in xenolithic clasts from the Sharps (H3.4) meteorite: Constraints on the origin and thermal processing

Primitive xenolithic clasts, often referred to as `` dark clasts", are well known in many regolith breccias. The Sharps H3.4 ordinary chondrite contains unusually large dark clasts up to similar to 1 cm across. Poorly-graphitized carbon (PGC), with Fe, Ni metal and described as `` carbon-rich aggregates", has been reported in these clasts (Brearley, 1990). We report detailed analyses of carbonaceous matter in several identical Sharps clasts using FTIR, Raman, C-XANES, and TEM that provide insight on the extent of thermal processing and possible origin of such clasts. We also prepared acid residues of the clasts using the HCl/HF method and conducted mass spectrometric analysis of the entrained noble gases.