Rhyolite

Title

Rhyolite

Identifier

SFM-31

Description

Hand Sample: Porphyritic rhyolite with medium-grained potassium feldspar and plagioclase feldspar phenocrysts in a dark red-brown matrix. Weathers with an orangish tinge.
Thin Section: Coarse-grained subhedral plagioclase feldspar phenocrysts in matrix. Opaques present.

Date

1/20/1969

Contributor

Western Minerals Inc.

Spatial Coverage

St. Francois Mountains Batholith, Missouri

Accrual Method

Purchased from Western Minerals, Inc.

Number of Thin Sections

1

Geolocation