Sphalerite

Sphalerite is a mineral that is composed of zinc sulfide (ZnS), and is the primary ore of zinc.

Sphalerite is usually brown or yellow in colour, but can also be red, orange, green, or black. It has a relatively high density and is typically used as an ore of zinc, although it is also of interest to mineral collectors due to its interesting crystalline shapes.

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Information about Sphalerite

Appearance

Sphalerite is typically a dark grey gun-metal coloured metallic mineral which is often found in association with other ore minerals, in fantastically detailed and interesting plates consisting of galena, chalcopyrite and pyrite, fluorite, calcite and quartz.

Uses and History

It is the primary ore of the metal Zinc, but is also an ore of cadmium, gallium, germanium and indium.

Along with its use in industry as an ore mineral, some sphalerite is actually cut and polished for jewellery. Fine quality cut pieces are a burnt golden orange colour similar to madiera Citrine.

It was named in 1847 after the Greek word ‘sphaleros’, which means ‘decieving’. This is due to its appearance, which is very similar to Galena and several other minerals, making it tricky to identify in the field.

Sphalerite was likely used to produce brass as far back as the 7th century – brass being an alloy of copper and zinc.

Locales

It’s nice to be able to say we do have some fine Sphalerites right here in the UK – the pieces from Smallcleugh Mine in Cumbria are world renowned amongst collectors.

We aren’t the only great locale though; there are some fantastic gemmy crystals found in the Picos del Europa mountain range of Spain, and some amazingly ‘sharp’ crystalline pieces come from Primorsky Krai, Russia.

I have also seen some very nice specimens from Namibia and South Africa and the USA.

Mineralogy

Chemistry
Zinc sulfide with the formula ZnS.
Colours and Variations
Gunmetal, light to dark brown, reddy-brown, red, green, black.
Streak
Brown to yellow
Luster
Adamantine to subadamantine
Transparency
Transparent to opaque
Fracture
Conchoidal
Crystal habit
Cubic, euhedral crystals and sometimes granular.
Mohs hardness
3.5 – 4
Fluorescence
Sometimes, very faint
Specific Gravity
3.9 – 4.1
Easiest testing method

Hazards and Warnings

Zinc is toxic when airborne during welding, causing ‘zinc fume fever’.

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Arabic:

  • السفاليريت

Hindi:

  • स्फेलेराइट

Portuguese:

  • esfalerita

Bengali:

Indonesian:

Punjabi:

English:

  • sphalerite

Italian:

Russian:

  • сфалерит

French:

  • sphalérite

Japanese:

  • 閃亜鉛鉱

Spanish:

  • esfalerita

German:

  • Sphalerit

Korean:

  • 섬아연석

Thai:

  • สฟาเลอไรต์

Gujurati:

Mandarin Chinese:

  • 閃鋅礦

Urdu:

Further Reading / External Links