Index No: NBM051740; Collected By: ; Sample Type: hand sample; Notes: Silicified, alunitized, rhyolitic welded ash-flow tuff; rock is patchwork of greenish matrix (aggregates of illite and quartz crystals) and pink partially altered alkali feldspar. Boytroidal hematite coats fractures, limonite-after-pyrite points disseminated in rock (XRD analysis by Li Hsu)