Aleksite is a rare lead-bismuth tellurium sulfosalt mineral with formula PbBi2Te2S2. This is a trigonal-hexagonal scalenohedral steel-gray mineral containing bismuth, lead, sulfur, and tellurium. It is an exceedingly rare mineral, only known from a very limited number of samples obtained from bismuth telluride assemblages. Very fine-grained, it is unlikely to be noticed in hand specimen and its identification requires ore petrology backed up by SEM analytical facilities. Associated minerals include other bismuth tellurides, galena, and gold.

General information

  • Formula: PbBi2Te2S2
  • Color: In polished section, very pale gray with slight greenish tint
  • Lustre: Metallic
  • Hardness: 2½
  • Specific Gravity: 7.80 (Calculated)
  • Crystal System: Trigonal.

Physical Properties of Aleksite

  • Cleavage: {???} Perfect
  • Color: Steel gray.
  • Diaphaneity: Opaque
  • Habit: Granular – Generally occurs as anhedral to subhedral crystals in matrix.
  • Hardness: 2.5 – Finger Nail
  • Luster: Metallic

Occurrence in Wales: aleksite was identified in a telluride-rich sample collected from Clogau Gold Mine in North Wales in the early 1980s (Bevins & Stanley, 1990). This represented only the second occurrence of the mineral worldwide.


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