Rocksday

Quartzite

Sandstone fused by metamorphism into an extremely hard rock of interlocked quartz grains.

Quartzite specimen
Photo: Gabriel Haute Maurienne, CC BY-SA 4.0, via Wikimedia Commons

How to identify quartzite

  • Breaks through the grains, not around them.
  • Scratches glass.
  • Smooth, sugary surface — not gritty.
  • Doesn't fizz in acid.

Often confused with

Where it's found

  • Baraboo, Wisconsin
  • Sioux Falls, South Dakota
  • Appalachian Mountains

Uses

Countertops, railroad ballast and silica.

Rock tumbling

Great for tumbling.

Did you know?

The pink Sioux Quartzite is so durable it was used to build much of Sioux Falls.

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

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