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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