igneous
Rhyolite
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale; typically pink, tan, or gray; aphanitic to porphyritic texture with quartz and alkali feldspar phenocrysts; dull to sub-vitreous luster.
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Physical properties
Hardness 6 on Mohs scale; typically pink, tan, or gray; aphanitic to porphyritic texture with quartz and alkali feldspar phenocrysts; dull to sub-vitreous luster.
Formation & geological history
Formed from the rapid cooling of silica-rich lava extruded from volcanoes, highly consistent with the Miocene volcanic geology of central Washington state.
Uses & applications
Used primarily as crushed stone in construction, decorative landscaping, and occasionally as a lapidary material.
Geological facts
Rhyolite is the extrusive equivalent of granite and often exhibits flow banding from movement while cooling.
Field identification & locations
Identify by its light color and fine-grained matrix containing visible quartz or feldspar crystals; common in volcanic regions worldwide.
