Thomsonite

A zeolite that forms radiating 'eye' patterns in pink, green and white inside basalt.

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

How to identify thomsonite

Small round eyes of radiating fibers in pink, green and white.
Set in dark basalt.
Hardness about 5.

Often confused with

Agate
Agate is harder and banded rather than radiating.
Compare side by side

Where it's found

North Shore of Lake Superior, Minnesota
Scotland
Italy

Uses

Cabochons and collector stones.

Rock tumbling

Can be tumbled with care.

Did you know?

Minnesota's Lake Superior shore is famous for gem thomsonite 'eyes'.

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