Figure F49. Photomicrograph showing plagioclase alteration in a troctolite. Plagioclase (pl) is preserved in the center. In addition to the typical coronitic replacement by chlorite and talc, plagioclase is altered to greenish brown clay (arrow) along the margins of the relics. Olivine is completely altered to sepentine and trains of magnetite that form mesh textures. Irregular networks of carbonate-clay veinlets (vn, high relief) cut the serpentinized olivine grains and follow former plagioclase/olivine grain boundaries (Sample 209-1275D-6R-1, 89–91 cm) (plane-polarized light: blue + gray filters; field of view = 2.75 mm; image 1275D

Figure F49. Photomicrograph showing plagioclase alteration in a troctolite. Plagioclase (pl) is preserved in the center. In addition to the typical coronitic replacement by chlorite and talc, plagioclase is altered to greenish brown clay (arrow) along the margins of the relics. Olivine is completely altered to sepentine and trains of magnetite that form mesh textures. Irregular networks of carbonate-clay veinlets (vn, high relief) cut the serpentinized olivine grains and follow former plagioclase/olivine grain boundaries (Sample 209-1275D-6R-1, 89–91 cm) (plane-polarized light: blue + gray filters; field of view = 2.75 mm; image 1275D_019).