The reclassification of weathering degree of Antarctic ordinary chondrites

There is a contradiction when categorizing some ordinary chondrites (OCs) from Grove Mountains (GRV), Antarctica, according to Wlotzka' s criteria. That is only a minor of metal and troilite (less than 20%) were replaced by oxide while silicates being partly weathered, especially along cracks. The weathering degree of these OCs are all W1 if categorized by the oxidation of metal and troilite; however, they should be W5 by the weathering degree of silicates. Therefore, we propose new criteria to categorize the weathering degree of these OCs, in which the weathering degree of metal and silicates are categorized into 5 and 4 progressive stages (they are W(m)0, W(m)1, W(m)2, W(m)3 and W(m)4 for metal and W(s)0, W(s)1, W(s)2 and W(s)3 for silicates), respectively. Consequently, meteorites GRV 021588, GRV 021636, GRV 021772 and GRV 021957 which can' t fit Wlotzka' s criteria are all W(m)1-W(s)1. Furthermore, GRV 023312 is W(m)3-W(s)0 type, which is the same with W3 in Wlotzka' s criteria.