Metamorphic mineral assemblages of slightly calcic pelitic rocks in and around the Taconic allochton. Southwestern Massachusetts and adjacent Connecticut and New York. circa 1966.

Album caption: Metamorphic mineral assemblages of slightly calcic pelitic rocks in and around the Taconic allochton. Photomicrographs of triply zoned plagioclase from (B0 sample 360-1 (cross-polarized light), showing the calcium-free rim in sharp contact with calcium-rich core. Compare with the profiles shown on figure 10. Southwestern Massachusetts and adjacent Connecticut and New York. ca. 1966. Published as figure 9-B in U.S. Geological Survey. Professional paper 1113. 1981.