Figure F58. Close-up photograph of a green silicified moderately amygdaloidal, aphyric volcanic rock from Unit 13 with vesicles as large as 5 mm in size, mostly filled with quartz, although some are lined by anhydrite-pyrite. Several hairline quartz-anhydrite-pyrite veins with 1- to 2-mm dark gray siliceous halos are also visible. The coarser vein is filled with anhydrite and minor pyrite (interval 193-1189B-10R-1, 2-14 cm).