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Figure F25. Thin section photomicrographs of altered olivine and groundmass. A, B. Completely altered microphenocrysts of olivine to green clay (rim) and calcite (clast in sediment; Sample 330-U1376A-5R-2, 125–127 cm; Thin Section 246): (A) plane-polarized light, (B) crossed polars. C, D. Olivine highly altered to green and brown clay and carbonate (moderately olivine-augite-phyric basalt; Sample 330-U1376A-6R-3, 103–106 cm; Thin Section 251): (C) plane-polarized light, (D) crossed polars. E, F. Highly altered groundmass of highly olivine-augite-phyric basalt (Sample 330-U1376A-5R-6, 97–99 cm; Thin Section 248; plane-polarized light), showing (E) secondary green clay minerals and (F) secondary hematite and palagonite.

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