Royal Gorge Rhyolite
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.
Western Minerals Inc.
Is Part Of
St. Francois Mountains Batholith, Missouri
Purchased from Western Minerals, Inc.
Number of Thin Sections