igneous
Porphyritic Rhyolite
Felsic Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale, grayish groundmass with prominent pinkish feldspar phenocrysts, and an aphanitic to glassy luster.
Identified More igneous →
Explore Porphyritic Rhyolite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 6-7 on the Mohs scale, grayish groundmass with prominent pinkish feldspar phenocrysts, and an aphanitic to glassy luster.
Formation & geological history
Formed from the rapid cooling of silica-rich lava at or near the Earth's surface during volcanic eruptions.
Uses & applications
Used locally as decorative gravel, in landscaping, and occasionally as a building stone.
Geological facts
Rhyolite is the extrusive equivalent of granite, sharing the same mineralogy but possessing a much finer texture due to rapid cooling.
Field identification & locations
Identify by its fine-grained gray matrix dotted with distinct lighter-colored crystal phenocrysts; commonly found near ancient volcanic regions.
