Proustite

A translucent scarlet silver sulfosalt that darkens when exposed to light.

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

How to identify proustite

Translucent scarlet crystals with a brilliant luster.
Darkens to gray in light.
Scarlet streak.

Often confused with

Cinnabar
Cinnabar is heavier and has no silver.
Compare side by side
Cuprite
Cuprite is darker and cubic.
Compare side by side

Where it's found

Chañarcillo, Chile
Freiberg, Germany
Mexico

Uses

Silver ore and collector specimens.

Rock tumbling

Not suitable for tumbling.

Did you know?

It's named after French chemist Joseph Proust.

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