Rocksday

Native Copper

Copper as a pure metal, often in branching, tree-like masses. Fresh surfaces are salmon-pink; old ones tarnish brown or green.

Native Copper specimen
Photo: Native_Copper_Macro_Digon3.jpg: “Jonathan Zander (Digon3)" derivative work: Materialscientist (talk), CC BY-SA 3.0, via Wikimedia Commons

How to identify native copper

  • Copper-red where scratched; brown or green tarnish elsewhere.
  • Heavy and malleable — it bends.
  • Branching, wiry or nugget shapes.
  • Shiny copper-red streak.

Often confused with

Where it's found

  • Keweenaw Peninsula, Michigan
  • Arizona
  • Ural Mountains, Russia

Uses

Ancient tools — Lake Superior's native copper was worked thousands of years ago.

Rock tumbling

Can be tumbled with care.

Did you know?

The Smithsonian's Ontonagon Boulder is a single 1.7-ton mass of Michigan copper.

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

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