Rocksday

Diorite

A 'salt-and-pepper' coarse-grained rock of white plagioclase and black hornblende, between granite and gabbro in composition.

Diorite specimen
Photo: Michael C. Rygel, CC BY-SA 3.0, via Wikimedia Commons

How to identify diorite

  • Roughly equal white and black speckles.
  • Coarse grains visible by eye.
  • Little or no glassy quartz, no pink feldspar.
  • Hard and heavy.

Often confused with

Where it's found

  • Guernsey, Channel Islands
  • Sierra Nevada, California
  • The Andes

Uses

Building stone and ancient sculpture.

Rock tumbling

Great for tumbling.

Did you know?

The famous statues of Gudea, ruler of Lagash around 2100 BC, are carved from hard diorite.

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