Rhyolite

Title

Rhyolite

Identifier

SFM-8

Description

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.

Date

1/20/1969

Contributor

Western Minerals, Inc.

Spatial Coverage

St. Francois Mtns. Batholith, Missouri

Temporal Coverage

Undifferentiated Van Erst Group

Accrual Method

Purchased from Western Minerals, Inc.

Number of Thin Sections

1

Geolocation