Figure F59. Relationship between volcanic fragments, anhydrite, and gypsum in Unit 3. Both images are from interval 193-1189B-2R-1, 11-14 cm. A. Anhydrite surrounded by and replaced along cleavage planes by fibrous gypsum. The opaque minerals are pyrite (in cross-polarized reflected light; width of view = 1.4 mm [Photomicrograph ID# 1189B_4; thin section 115]). B. Gypsum partly replacing anhydrite, which has partially replaced altered volcanic clasts (in plane-polarized light; width of view = 1.4 mm [Photomicrograph ID# 1189B_25; thin section 115]).