Figure F33. Remnant perlite texture in the altered groundmass of a completely altered, aphyric massive rock (Unit 21), where the arcuate cracks have been preserved despite replacement of the glassy volcanic groundmass by quartz, chlorite, and clay minerals (Sample 193-1189B-13R-1 [Piece 10, 52-54 cm]; width of view = 2.75 mm. Photomicrograph ID# 1189B

Figure F33. Remnant perlite texture in the altered groundmass of a completely altered, aphyric massive rock (Unit 21), where the arcuate cracks have been preserved despite replacement of the glassy volcanic groundmass by quartz, chlorite, and clay minerals (Sample 193-1189B-13R-1 [Piece 10, 52-54 cm]; width of view = 2.75 mm. Photomicrograph ID# 1189B_58; thin section 129).