Figure F5. Photomicrographs of silicified volcanic rock (Sample 331-C0016B-1L-CC, 12–14 cm). Sulfide phases are indicated. Py = pyrite, Sp = sphalerite, Cp = chalcopyrite, Gn = galena. A. Representative view of sample. Intergrown quartz-muscovite/illite-sphalerite-pyrite (plane-polarized light [PPL]; ×5). B. Same as A (reflected light [RL]; ×5). C. Coarse anhydrite crystal (blue interference colors) overgrowing quartz, muscovite/illite, and sulfides (cross-polarized light; ×5). D. Sphalerite overgrown by galena, which is overgrown by pyrite, which is overgrown by chalcopyrite (RL; ×10). E. Higher magnification view of the galena-pyrite-chalcopyrite overgrowth boxed in D (RL; ×40).
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