Royal Gorge Rhyolite

Title

Royal Gorge Rhyolite

Identifier

SFM-21

Description

Hand Sample: Porphyritic medium-grained phenocrysts of potassium feldspar in a dark purple-red groundmass. Weathers to white and orange-brown.
Thin Section: Primarily matrix with some very-fine anhedral grains of a mineral with high blue birefringence. Some fine-grained anhedral well-weathered and fractured quartz grains. 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