Chalcedony

Quartz made of microscopic fibers. Plain chalcedony is soft blue-gray and often grows in bubbly, grape-like crusts.

Chalcedony specimen — Photo: Robert M. Lavinsky, CC BY-SA 3.0, via Wikimedia Commons

How to identify chalcedony

Waxy, translucent and milky.
Bubbly 'botryoidal' surfaces are common.
No crystal faces; scratches glass.

Often confused with

Opal
Opal is softer and lighter, and may show color play.
Compare side by side
Agate
Agate is chalcedony with clear banding.
Compare side by side

Where it's found

Oregon
Namibia
Turkey
Brazil

Uses

Carvings, beads and cameos.

Rock tumbling

Great for tumbling.

Did you know?

Agate, carnelian, onyx and chrysoprase are all varieties of chalcedony.

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