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Andesite

An intermediate volcanic rock typical of explosive volcanoes above subduction zones.

Andesite specimen
Photo: Photographer: Siim Sepp, 2005, CC BY-SA 3.0, via Wikimedia Commons

How to identify andesite

  • Medium gray.
  • White feldspar crystals and dark specks scattered in a fine-grained base.
  • Heavier than rhyolite, lighter than basalt.
  • No visible quartz.

Often confused with

Where it's found

  • The Andes
  • Cascade Range, USA
  • Japan
  • Indonesia

Uses

Construction aggregate and building stone.

Rock tumbling

Can be tumbled with care.

Did you know?

It's named after the Andes, where it makes up many of the volcanoes.

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