Figure F16. Photomicrographs showing plagioclase phenocrysts. I. Partially altered olivine phenocrysts in Subunit 3b (Sample 197-1205A-8R-1, 59-61 cm) (plane-polarized light; field of view = 1.25 mm; photomicrograph 1205A-190). J. Partially altered olivine phenocryst rimmed by biotite in Unit 27 (Sample 197-1205A-43R-2, 58-60 cm) (plane-polarized light; field of view = 5 mm; photomicrograph 1205A-274).