Topaz

A fluorine-bearing silicate and the Mohs reference for hardness 8. Crystals are often clear with sharp, diamond-shaped cross-sections.

Topaz specimen — Photo: Parent Géry, CC BY-SA 3.0, via Wikimedia Commons

How to identify topaz

Harder than quartz (8).
One perfect cleavage across the crystal — flat, mirror-like breaks.
Feels heavier than quartz of the same size.
Prisms with lengthwise striations.

Often confused with

Quartz
Quartz is softer, lighter and has no cleavage.
Compare side by side
Diamond
Diamond is harder still and has a much stronger, oily-bright luster.
Compare side by side

Where it's found

Ouro Preto, Brazil
Topaz Mountain, Utah
Ural Mountains, Russia
Pakistan

Uses

Gemstones.

Rock tumbling

Can be tumbled with care. Its cleavage makes it prone to chipping.

Did you know?

Almost all blue topaz is colorless topaz that has been irradiated and heated.

Think you could spot it from a blurry close-up?

Play today's Rocksday