Astromat

Accelerator mass spectrometry analysis of 36Cl concentrations in small (~1 mg) splits from three stones of interest (SOI), OREX-800023-0 (mottled), OREX-800055-0 (angular) and OREX-800088-0 (hummocky), as well as a 14.4 mg split of the homogenized powder of aggregate sample, OREX-800117-0. The samples were dissolved in HF/HNO3 and a small aliquot of the dissolved sample was taken for chemical analysis by ICP-OES. The 36Cl concentrations in the SOIs range from 82 to 132 dpm/kg, compared to a 36Cl concentration of 101 dpm/kg in the aggregate sample. The high 36Cl concentrations indicate that 36Cl is dominated by neutron-capture production on 35Cl in the top 1-2 m of Bennu's surface.