Ulexite

A fibrous borate whose parallel fibers pipe light like fiber optics.

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

How to identify ulexite

Silky white fibers in parallel bundles.
Polished slabs show text from underneath on top.
Light and soft.

Often confused with

Gypsum
Satin spar gypsum is silky but doesn't transmit images.
Compare side by side

Where it's found

Boron, California
Turkey
Argentina
Chile

Uses

Borate ore.

Rock tumbling

Not suitable for tumbling.

Did you know?

It's nicknamed 'TV rock' because it projects the image beneath it onto its top surface.

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