Olivine

Olive-green silicate that makes up most of Earth's upper mantle. Gem-quality olivine is called peridot.

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

How to identify olivine

Bottle- to olive-green glassy grains.
Often as sugary green clumps in black basalt.
No cleavage — breaks like glass.
Hard enough to scratch glass.

Often confused with

Epidote
Epidote is darker pistachio green and grows in striated prisms with one cleavage.
Compare side by side
Tourmaline
Green tourmaline grows in long prisms with triangular cross-sections.
Compare side by side

Where it's found

Papakōlea, Hawaii
San Carlos, Arizona
Zabargad Island, Egypt
Pakistan

Uses

Peridot gems, foundry sand and refractory bricks.

Rock tumbling

Can be tumbled with care. Most rough is small and fractured.

Did you know?

Hawaii's Papakōlea Beach is green because its sand is mostly olivine grains.

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