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Estimation of Fe 3+ from electron microprobe analyses: observations on calcic amphibole and chlorite
Author(s) -
JACOBSON C. E.
Publication year - 1989
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.1989.tb00613.x
Subject(s) - amphibole , chlorite , epidote , electron microprobe , microprobe , geology , mineralogy , schist , magnetite , analytical chemistry (journal) , geochemistry , chemistry , metamorphic rock , paleontology , environmental chemistry , quartz
Metabasites and metagreywackes from the Pelona and Rand Schists of southern California were analysed using three different electron microprobes. For all three instruments, the estimated Fe 3+ contents of calcic amphibole, chlorite and epidote are positively correlated. For some samples, there is an additional correlation between high estimated Fe 3+ and the presence of magnetite. These results imply that microprobe analyses can be used to discern relative differences in Fe 3+ . However, microprobe data and calculations on the sensitivity of the correction procedures to systematic analytical errors indicate that estimated values of Fe 3+ are not significant in an absolute sense. Thus, estimates of Fe 3+ are meaningful when comparing samples analysed with a single microprobe, but must be used with caution when comparing analyses obtained on more than one probe.