Class : Sulfides and sulfosalts
    Subclass : Tellurides
    Crystal system : Trigonal
    Chemistry : Bi₂Te₂S
    Rarity : Uncommon

Tetradymite is the most common telluride. It is a mineral that is found mainly in low to high temperature hydrothermal gold veins. It is associated with different tellurides (hessite, altaite, petzite), native bismuth and native gold. Its name comes from the Greek tetradumos (quadruple) in allusion to its twinned crystals. Tetradymite has a metallic luster and a steel gray color that tarnishes to grayish to iridescent. This mineral has a perfect cleavage that ensures a flow in flexible lamellae like molybdenite. Its crystals are rarely well formed : they are acute rhombohedra with striated faces, evoking hexagonal prisms, with frequent twins of 4 individuals. Tetradymite occurs more often in small foliated or lamellar masses. It is the main ore of tellurium and an accessory source of bismuth.

Main photo : Tetradymite and native gold from Jílové u Prahy, Czech Republic © Bohuslav Bures

Twinning with 4 individuals on {01.8} and on {01.5} is known.

No fakes listed for this mineral species.