Gas-rich minerals in the Allende meteorite: Attempted chemical characterization
Abstract
A ten-step etching experiment with HNO 3 was performed on a chromite-carbon residue from Allende, in order to characterize the HNO 3-soluble, minor phase "Q" that contains most of the primordial Ar, Kr, Xe. Each etch fraction was analyzed by neutron activation analysis for Cr, Fe, Co, Ir, and Au. The results suggest that Q consists of two minerals, each comprising about 5% of the residue. Phase Q1, of Fe/Cr ratio >20, in soluble in cold, dilute HNO 3, and seems to contain most of the heavy noble gases. It may be an HCl-insoluble sulfide of nominal composition (Fe 84Ni 12Cr 4)S x. Phase Q2, of Fe/Cr ratio ∼0.5 and somewhat enriched in Co, is slowly soluble in hot, conc. HNO 3, and seems to be at least an order of magnitude poorer in heavy noble gases than Q1. It may be daubréelite, or an acid-soluble variety of chromite.
- Publication:
-
Earth and Planetary Science Letters
- Pub Date:
- January 1977
- DOI:
- 10.1016/0012-821X(77)90091-7
- Bibcode:
- 1977E&PSL..33..401G
- Keywords:
-
- Carbonaceous Chondrites;
- Meteoritic Composition;
- Mineralogy;
- Rare Gases;
- Abundance;
- Chromites;
- Etching;
- Neutron Activation Analysis;
- Nitric Acid;
- Sulfides