Figure F45. A. Photomicrograph from Unit 2 in Sample 183-1139A-56R-1, 37-40 cm (in plane-polarized light), showing sanidine phenocrysts in an altered feldspathic, trachytic groundmass. B. Photomicrograph of sanidine and quartz phenocrysts at the top of Unit 4 from Sample 183-1139A-57R-1, 120-123 cm (in cross-polarized light).