Rocksday

Rhyolite

The volcanic twin of granite — same chemistry, but erupted and cooled fast, so its crystals are tiny.

Rhyolite specimen
Photo: Benhoff, CC BY-SA 3.0, via Wikimedia Commons

How to identify rhyolite

  • Light pink, tan or gray.
  • Fine-grained, often with swirling flow bands.
  • May have small visible quartz or feldspar crystals.
  • Lighter in color and weight than basalt.

Often confused with

Where it's found

  • Yellowstone, Wyoming
  • Owyhee region, Oregon
  • Nevada
  • Queensland, Australia

Uses

Aggregate and ornamental stones like 'rainforest jasper'.

Rock tumbling

Great for tumbling.

Did you know?

The yellow walls of the Grand Canyon of the Yellowstone are rhyolite altered by hot water.

Think you could spot it from a blurry close-up?

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