Index No: NBM053690; Collected By: ; Sample Type: hand sample; Notes: Rock chip sample of vuggy silica+alunite altered silicic tuff from top of E-W ridge east of alunite ridge of sample 5205. Sample is combination of chips from 2 intergradational alteration types at top of ridge: porous quartz-alunite alteration, and dense total quartz replacement, with very fine-grained chalcedonic silica. Lithic fragments in dense rock commonly have good vuggy silica texture. It appears that tuff matrix was replaced by chalcedony, but some of the lithic clasts were leached. -Weiss, 6/25/95.