Willemite

Willemite


Composition: Zn2SiO4
Crystal System : Trigonal
Lustre : Vitreous, resinous
Hardness : 5.5
Specific Gravity : 4.05-4.19
References: Gebhard (1999)

Occurrence

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

Notable Finds

Willemite was encountered quite early in the mine's history, high in the first oxidation zone; a specimen from c. 1915 comprises willemite epimorphs after mimetite, associated with smithsonite (Gebhard, 1999). A later find of gemmy blue willemite crystals to 10 mm on white calcite established Tsumeb as an important locality for willemite, although Gebhard (op. cit.) does not record the exact location in the mine for this discovery. In the third oxidation zone, between 43 and 46 levels, lemon-yellow willemite crystals, to 10 mm, were associated with pale blue rosasite or green adamite (Gebhard, op. cit.).