Figure F52. Basalt showing total replacement of olivine phenocrysts (upper left) and groundmass by smectite and Fe oxyhydroxide in Sample 192-1185B-12R-1 (Piece 6, 40-44 cm). The photomicrograph is of a light yellow-brown halo along a sparry calcite and micritic sediment vein (partially visible, bottom right). Plagioclase is unaltered. Miarolitic voids are filled with zoned smectite (center left and below center right) (overall alteration = 15%; field of view = 5.5 mm; plane-polarized light; photomicrograph ID# 1185B

Figure F52. Basalt showing total replacement of olivine phenocrysts (upper left) and groundmass by smectite and Fe oxyhydroxide in Sample 192-1185B-12R-1 (Piece 6, 40-44 cm). The photomicrograph is of a light yellow-brown halo along a sparry calcite and micritic sediment vein (partially visible, bottom right). Plagioclase is unaltered. Miarolitic voids are filled with zoned smectite (center left and below center right) (overall alteration = 15%; field of view = 5.5 mm; plane-polarized light; photomicrograph ID# 1185B_213).