Very common mineral of the sulfide class.


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Origin of name: from Greek σφαλεροζ "sphaleros" (treacherous), because it was often confused with galena, a major lead ore. Georgius Agricola, 1494 - 1555, the German scholar and one of the fathers of mineralogy, called it blende, from the German verb "blenden" = to blind, deceive. In 1847 it was named sphalerite by the German theologian, philosopher and later professor of mineralogy, Ernst Friedrich Glocker.

Synonyms and trade names: zinc blende, Black Jack. Ocassionally one encounters names like ruby blende for red, cleiophane for green and honey blende for yellow sphalerite.

Can be confused with: rough sphalerite is easily confused with the lead ore galena. Facetted stones might be confused with other gems like scheelite, sphene (titanite) chrysoberyl, zircon, cassiterite or rutile. However, due to it's peculiar physical properties, like high density, single refraction, very high refractive index and dispersion, identification is usually quite simple and straightforward.

Localities: worldwide, including Antarctica, almost 20.000 localities are known. Important sources for gem quality material are Spain, Mexico, China and Brazil.


Fine sphalerite from Brazil

Handling: sphalerite is soft and very sensitive to heat, acids and brines. On top of that is has perfect cleavage in six directions. All this renders sphalerite unsuitable for use in jewellery.

Worth knowing: sphalerite may contain up to 67% of zinc, which makes it the prime zinc ore.


Gemmological Properties of Sphalerite

Crystal system:
Mohs hardness:
3.5 to 4
Specific gravity:
3.9 to 4.2
Refractive index:
singly refractive, 2.368 to 2.49 (with high Fe-content)
Max. Birefringence:
none, may show anomalous birefringence due to strain
usually yellow-orange to red, sometimes none
adamantine to greasy
uneven conchoidal, brittle
yellow, orange, red, green, brown, black, rarely colourless