Figure F38. Typical coronitic alteration of olivine, Unit II. A, B. Grain edge rimmed by a typical corona, with a rim of cryptocrystalline chlorite (Chl), tremolite (Tr), and talc (Tc) that has formed between plagioclase (Pl) and relict olivine (Ol) in clinopyroxene-bearing olivine gabbro (Thin Section 41; Sample 345-U1415J-7G-1, 35–38 cm [Piece 6]). C, D. Olivine with well-developed coronae, surrounded by plagioclase. Note the lack of radial fractures (Thin Section 40; Sample 345-U1415J-7G-1, 28–31 cm [Piece 5]). E, F. Clinopyroxene oikocryst-bearing troctolite/gabbronorite in which pseudomorphic replacement of olivine by tremolite and chlorite ± talc (Tc) is concentrated around a chlorite vein that cuts magmatic foliation with a high intersection angle. Amp = amphibole. A, C, and E are under plane-polarized light; B, D, and F are under crossed polars.
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