Gemdle

Rhyolite

browngray

Rhyolite, a brown/gray mineral
Tõnis Saadre · CC BY-SA 4.0
ColourBrown, Gray

What is Rhyolite?

Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent of granite.

Can you spot Rhyolite?

Test yourself on photos of Rhyolite and lookalikes:

Frequently asked questions

How hard is Rhyolite?
Rhyolite's hardness varies; see the property table above.
What colour is Rhyolite?
Rhyolite is typically brown, gray.