Galena

Galena


Composition: PbS
Crystal System : Cubic
Colours: Lead-grey
Lustre : Metallic, dull
Hardness (H) : 2.5
Specific Gravity (S.G) : 7.58

Distribution

Abundant. An important ore mineral throughout the Tsumeb deposit, but well-formed crystals are uncommon.

Occurrence

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

Paragenetic and General Notes

The most important primary lead mineral at Tsumeb, but forming late in the hypogene paragenesis.

Well-formed crystals of galena are somewhat uncommon at Tsumeb but they occur, typically, as combinations of cube {100} and octohedron {111} faces.  Twinning is quite commonly observed, with "spinel" twins (on {111}) often developed and highly prized as specimens.  Crystal faces of Tsumeb galena are commonly striated, with a pattern that is probably indicative of lamellar twinning which may be cause by mechanical deformation (see Ramdohr, 1980).

Galena is reported to form pseudomorphs after the following minerals:  calcite (rare).

The following minerals are reported to form pseudomorphs after galena:  cerussite (rare); rosasite (rare).