Distinctive features:  
Aphantitic, buff to greyish flow-banded rock, often containing spherulites or phenocrysts of quartz and feldspar.

Colour: 
Buff to greysih, banded.

Texture and granularity: 
Aphanitic to very fine-grained.

Composition: 
Same as granite, but the crystals are too small to see without using a volcanoes.

Field associations: 
As thick lava flows from acidic volcanoes.

Varieties:
Spherulitic rhyolite, which contains rounded bodies (spherules) of microcrystalline quartz and feldspar.

 

Worldwide.

 

Aggregate.