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Metallic copper in ordinary chondritesMetallic Cu of moderately high purity (approximately 985 mg/g Cu, approximately 15 mg/g Ni) occurs in at least 66% of ordinary chondrites (OC) as heterogeneously distributed, small (typically less than or equal to 20 micrometers) rounded to irregular grains. The mean modal abundance of metallic Cu in H, L and LL chondrites is low: 1.0 to 1.4 x 10(exp -4) vol%, corresponding to only 4 - 5 % of the total Cu in OC whole rocks. In more than 75% of the metallic-Cu-bearing OC, at least some metallic Cu occurs at metallic-Fe-Ni-troilite grain boundaries. In some cases it also occurs within troilite, within metallic Fe-Ni, or at the boundaries these phases form with silicates or chromite. Ordinary chondrites that contain a relatively large number of occurrences of metallic Cu/sq mm have a tendency to have experienced moderately high degrees of shock. Shock processes can cause local melting and transportation of metallic Fe-Ni and troilte; because metallic Cu is mainly associated with these phases, it also gets redistributed during shock events. In the most common petrographic assemblage containing metallic Cu, the Cu is adjacent to small irregular troilite grains surrounded by taenite plus tetrataenite; this assemblage resembles fizzed troilite and may have formed by localized shock melting or remelting of a metal-troilite assemblage.
Document ID
19950051527
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Rubin, Alan E.
(California Univ. Los Angeles, CA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Meteoritics
Volume: 29
Issue: 1
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
95A83126
Funding Number(s)
CONTRACT_GRANT: NAGW-3535
Distribution Limits
Public
Copyright
Other

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