Hand Sample: Holocrystalline fine-to-medium-grained phaneritic rhyolite with quartz, biotite, and plagioclase crystals generally no larger than 2mm. Weathers to brownish-orange.
Thin Section, XPL: 35% medium-grained anhedral quartz and subhedral plagioclase feldspar crystals surrounded by very-fine grained quartz crystals. Small patches of very-fine-grained biotite interspersed. Opaques present.
Western Minerals, Inc.
Is Part Of
St. Francois Mtns. Batholith, Missouri
Undifferentiated Van Erst Group
Purchased from Western Minerals, Inc.
Number of Thin Sections