Rocksday

Hornfels

A dense, very hard rock baked by the heat of nearby magma.

Hornfels specimen
Photo: User Fed on ru.wikipedia, Public domain, via Wikimedia Commons

How to identify hornfels

  • Dark, fine-grained and very hard.
  • Breaks with sharp, splintery edges.
  • Rings when tapped.

Often confused with

Where it's found

  • Skiddaw, England
  • Sierra Nevada, California
  • Around granite intrusions worldwide

Uses

Aggregate.

Rock tumbling

Great for tumbling.

Did you know?

The 'Musical Stones of Skiddaw', a 19th-century rock xylophone, were made of hornfels.

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

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