Sphalerite

Zinc sulfide and the main ore of zinc. Its resinous, honey-to-black crystals can look metallic or almost gem-like.

Sphalerite specimen — Photo: Ivar Leidus, CC BY-SA 4.0, via Wikimedia Commons

How to identify sphalerite

Resinous, 'tree-sap' luster.
Six directions of cleavage — sparkly broken surfaces.
Pale yellowish streak, even from black pieces.
Smells of rotten eggs in hydrochloric acid.

Often confused with

Galena
Galena is silvery, truly metallic and much heavier; they often occur together.
Compare side by side
Garnet
Garnet is harder and has no cleavage.
Compare side by side

Where it's found

Picos de Europa, Spain
Tri-State district, USA
Elmwood, Tennessee

Uses

Zinc for galvanizing steel and brass.

Rock tumbling

Not suitable for tumbling.

Did you know?

The name comes from Greek sphaleros, 'treacherous' — miners kept mistaking it for galena.

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