Formula: Fe3+3Bi5O9(Te4+O3)(Te6+O4)2.9H2O
Tellurite, bismuth-bearing mineral
Crystal System: Tetragonal or Hexagonal
Specific gravity: 5.59 measured
Hardness: 3
Streak: Yellow
Colour: Yellow, orange to brown, yellow-brown
Solubility: Fuses easily to a red glass and begins to evolve TeO2 shortly after the loss of water. It is readily soluble in cold 16% hydrochloric acid or 10% nitric acid

Hydrothermal environments

Yecoraite occurs in fractures in a quartz vein emplaced in quartz monzonite, an oxidation product of tetradymite and pyrite. Associated minerals include tetradymite, pyrite, chalcopyrite, quartz and iron oxides (HOM).


At the type locality, the San Martín de Porres Mine, Yécora, Yécora Municipality, Sonora, Mexico, yecoraite is found in quartz veins that cut granite, as pitchy or resinous masses intimately associated with tetradymite, often penetrating along cleavage. Other associated phases include goethite, chalcopyrite, pyrite, and two unidentified tellurites-tellurates of bismuth and iron. No crystals were found (AM 71.1547). Yecoraite is an oxidation product of tetradymite and pyrite (Mindat).

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