R. T. Dodd, 1972. "Calcium in Chondritic Olivine", Studies in Earth and Space Sciences, R. Shagam, R. B. Hargraves, W. J. Morgan, F. B. Van Houten, C. A. Burk, H. D. Holland, L. C. Hollister
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The abundance of calcium in olivine from 14 equilibrated low-iron chondrites was determined by microprobe analysis. With two exceptions (Shaw and Kunashak), median CaO abundances fall between 0.03 and 0.06 wt percent, substantially lower than those encountered in type 3 chondrites (for example, 0.15 percent in Sharps). It appears that much of the calcium in type 3 olivine was expelled during the metamorphic transition from type 3 to type 4. By contrast, changes from type 4 to type 6 were modest, though the data suggest slight calcium depletion in this interval.
High CaO contents (0.09 and 0.07 percent) in the Kunashak and Shaw chondrites, both type 6, suggest unusual thermal histories for these meteorites: shock reheating in the former case, and unusually high metamorphic temperatures in the latter.