Sphalerite

Sphalerite


Composition: ZnS
Crystal System : Cubic
Colours: Pale-brown, dark-brown, reddish-brown, black, green
Lustre : Adamantine, resinous
Hardness (H) : 3.5-4.0
Specific Gravity (S.G) : 3.9-4.2
References: Gebhard (1999)

Distribution

Abundant. A major component of the sulphide mineralisation throughout the Tsumeb deposit. However, well-formed crystals are rare.

Occurrence

  • Hypogene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

Crystallised specimens of sphalerite from the first oxidation zone are quite rare; however, the Wilhelm Klein collection at Harvard University includes specimens of crystallised sphalerite from 8 Level (ref., for example, Harvard # 127244). Gebhard (1999) records a 6 by 3 cm cluster of sphalerite crystals to 30 mm, recovered from 28 Level in the second oxidation zone. In the third oxidation zone, a few specimens of small red sphalerite crystals on dolomite were found.

Paragenetic and General Notes

Sphalerite very rarely forms euhedral, macroscopic crystals at Tsumeb, but it is an economically important component of the massive and disseminated sulphide ores throughout the deposit.

Gebhard (1999) notes that the red iron-rich sphalerite is considerably more abundant than the green, iron-defficient variety; however, the latter does occur at Tsumeb and is triboluminescent.

Keller (1977) considers sphalerite to be older than enargite, tennantite and galena in the hypogene paragenesis.