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Figure F21. Photomicrographs of composite veins from Hole U1382A basalt. A. Irregular and branching vein (500 µm thick) filled with saponite and disseminated opaque spherical pyrite (<10 µm) (plane-polarized light) (Sample 336-U1382A-12R-1, 83–86 cm). B. Microvein (<10 µm across) with thin (100 µm) irregular alteration front extending in a subcryptocrystalline (devitrified) mesostasis (plane-polarized light) (Sample 336-U1382A-7R-2, 70–73 cm). C. Mixed Fe oxyhydroxide and smectite vein in microcrystalline groundmass, lacking alteration halos (plane-polarized light) (Sample 336-U1382A-5R-3, 29–32 cm). D. Smectite vein (0.2 mm thick) in medium-grained basalt composed of fresh plagioclase, clinopyroxene, and Ti-magnetite and partially altered olivine and interstitial mesostasis (plane-polarized light) (Sample 336-U1382A-12R-3, 35–38 cm).

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