Composition: CdS
Crystal System : Hexagonal
Colours: Mustard-yellow, orange-yellow, red
Lustre : Adamantine, resinous
Hardness (H) : 3.0-3.5
Specific Gravity (S.G) : 4.8-4.9
References: Strunz et al. (1958a)


Very rare (though easily overlooked). First, second and third oxidation zones.


  • Hypogene
  • Supergene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

As prismatic crystals to 1 mm on wurtzite from the first oxidation zone. As tiny ochre-coloured crystals on smithsonite in the second oxidation zone (Gebhard, 1999). As part of the type assemblage for sidpietersite in the third oxidation zone.

Paragenetic and General Notes

As rare microcrystals associated with oxidising sulphides. Crystals occur on sulphide surfaces and on secondary minerals such as smithsonite and are therefore probably of supergene origin. Microscopic (colloidal?) inclusions of greenockite may account for the colour of yellow smithsonite.