Figure F58. Typical gray, fine-grained basalt illustrating total replacement of the olivine phenocrysts and groundmass glass by smectite in Sample 192-1185B-17R-3 (Piece 1A, 1-3 cm). Plagioclase and clinopyroxene are unaltered (overall alteration = 15%-20%; field of view = 5.5 mm; plane-polarized light; photomicrograph ID# 1185B

Figure F58. Typical gray, fine-grained basalt illustrating total replacement of the olivine phenocrysts and groundmass glass by smectite in Sample 192-1185B-17R-3 (Piece 1A, 1-3 cm). Plagioclase and clinopyroxene are unaltered (overall alteration = 15%-20%; field of view = 5.5 mm; plane-polarized light; photomicrograph ID# 1185B_217).