igneous
Rhyolite
Extrusive Felsic Igneous Rock
Hardness of 6 on the Mohs scale, colors range from light gray, pink, to reddish-brown, aphanitic to porphyritic texture, dull to vitreous luster, specific gravity around 2.35 to 2.6
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Physical properties
Hardness of 6 on the Mohs scale, colors range from light gray, pink, to reddish-brown, aphanitic to porphyritic texture, dull to vitreous luster, specific gravity around 2.35 to 2.6
Formation & geological history
Formed from the rapid cooling of silica-rich lava at or near the Earth's surface, typically associated with explosive continental volcanic eruptions
Uses & applications
Used occasionally as aggregate, crushed stone in construction, or polished for decorative landscaping and ornamental stones
Geological facts
Rhyolite is the extrusive equivalent of granite, possessing the same mineralogy but cooling much more quickly, which prevents large crystals from forming
Field identification & locations
Identify by its fine-grained groundmass often containing phenocrysts of quartz and feldspar; commonly found in volcanic regions worldwide
