Greenockite

wurtzite

sphalerite

Formula: CdS
Sulphide, wurtzite group, dimorph of hawleyite
Specific gravity: 4.8 to 4.9
Hardness: 3 to 3½
Streak: Orange-yellow to brick red
Colour: Yellow to red.
Environments

Igneous environments
Hydrothermal environments rarely

Greenockite occurs as earthy coatings, especially on sphalerite, rarely as crystals in cavities in mafic igneous rocks, and in high-temperature hydrothermal vein deposits. Associated minerals include sphalerite, smithsonite, prehnite and zeolites at low temperature, and cassiterite, tetrahedrite, herzenbergite, chalcopyrite and other sulphides at high temperature (HOM, Mindat).

At the South Comet Mine, Dundas, Tasmania, Australia, some sphalerite crystals have a coating of greenockite (AJM 12.2.72).

At the Guerrero mine, Taxco municipality, Mexico, greenockite has been found as coatings on sphalerite (Minrec 42.5.430).

At Tsumeb, Oshikoto region, Namibia, the zinc-cadmium sulphides of the wurtzite - greenockite series were scattered through a lead-rich, zinc-deficient mineral assemblage containing moderate amounts of pyrite, tennantite, bornite, chalcocite and digenite, within the cadmium bearing zone which appeared to have escaped supergene effects (AM 42.184). Greenockite occurs only in association with sphalerite between 140 and 200 metre depths (R&M 93.6.545).

Common impurities: Zn

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