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Figure F41. Thin section photomicrographs of completely altered olivine. A. Alteration to iddingsite, hematite, and minor carbonate (highly plagioclase-olivine-augite-phyric basalt breccia) (Sample 330-U1374A-24R-4, 100–102 cm; Thin Section 160; plane-polarized light). B. Detail of association of carbonate and iddingsite after olivine (highly plagioclase-olivine-augite-phyric basalt breccia) (Sample 330-U1374A-25R-2, 128–131 cm; Thin Section 163; plane-polarized light). C, D. Olivine completely altered to iddingsite and carbonate (aphyric to moderately olivine-phyric basalt breccia) (Sample 330-U1374A-24R-4, 100–102 cm; Thin Section 160): (C) plane-polarized light, (D) crossed polars. E, F. Olivine completely altered to iddingsite, Fe oxyhydroxides, and large amount of carbonate in the interior portions of the altered phenocrysts (moderately plagioclase-phyric basalt) (Sample 330-U1374A-48R-8, 20–23 cm; Thin Section 205): (E) plane-polarized light, (F) crossed polars.

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