igneous
Rhyolite
Rhyolite (felsic extrusive igneous rock)
Hardness: 6 on the Mohs scale; Color: Pink, tan, grey, or reddish; Luster: Dull to vitreous; Crystal structure: Aphanitic (fine-grained) to porphyritic, often with quartz and feldspar phenocrysts; Specific Gravity: 2.35 - 2.65
- Hardness
- 6 on the Mohs scale
- Color
- Pink, tan, grey, or reddish
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6 on the Mohs scale; Color: Pink, tan, grey, or reddish; Luster: Dull to vitreous; Crystal structure: Aphanitic (fine-grained) to porphyritic, often with quartz and feldspar phenocrysts; Specific Gravity: 2.35 - 2.65
Formation & geological history
Formed from the rapid cooling of silica-rich lava extruded from volcanoes, typically occurring in continental volcanic arcs and calderas.
Uses & applications
Used occasionally as decorative stone, crushed stone in construction, or polished into cabochons for jewelry.
Geological facts
Rhyolite is the extrusive equivalent of granite, meaning they share the exact same chemical and mineral composition, but rhyolite cools much faster on the Earth's surface.
Field identification & locations
Identify by its fine-grained matrix, light colors (pinkish/tan), and occasional embedded crystals of quartz or feldspar. Commonly found in volcanic regions worldwide.
