Cadmoselite is a rare cadmium selenide mineral with chemical formula CdSe. It is a rare hexagonal cadmium selenide mineral, black to grey in color. It was first described in 1957 as an occurrence in Tuva. The mineral occurs as interstitial grains in sandstone formed under reducing alkaline diagenetic conditions.

Cadmoselite crystallizes in the hexagonal system and occurs as black to pale grey opaque crystals and grains.

General information

  • Formula: CdSe
  • Color: Black
  • Lustre: Adamantine, Resinous
  • Hardness: 4
  • Specific Gravity: 5.47
  • Crystal System: Hexagonal.


  • Transparency: Opaque
  • Streak: Black
  • Tenacity: Brittle
  • Cleavage: Perfect
  • Density: 5.47 g/cm3 (Measured) and 5.807 g/cm3 (Calculated)

Occurrence: In sedimentary strata, under reducing secondary conditions of medium to high alkalinity (Ust’Uyuk deposit, Russia).

Association: Ferroselite, clausthalite, cadmian sphalerite, selenium, greenockite, pyrite, laumontite, calcite (Ust’Uyuk deposit, Russia).


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