Datolite

A calcium borosilicate forming pale green glassy crystals, or porcelain-like nodules in Michigan's copper country.

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

How to identify datolite

Pale green, many-faced glassy crystals.
Michigan nodules look like porcelain, often tinted by copper.
Hardness about 5.

Often confused with

Prehnite
Prehnite forms bubbly crusts rather than sharp crystals.
Compare side by side

Where it's found

Keweenaw Peninsula, Michigan
New Jersey
Dalnegorsk, Russia

Uses

Collector specimens and cabochons.

Rock tumbling

Can be tumbled with care.

Did you know?

Copper-stained datolite nodules from Michigan's mines can be cut to show red, pink and orange.

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