Greenockite

Greenockite is a rare cadmium mineral that consists of cadmium sulfide, CdS, in crystalline form. Greenockite crystallizes in the hexagonal system. It occurs as massive encrustations and as six-sided pyramidal crystals which vary in color from a honey yellow through shades of red to brown. The Mohs hardness is 3 to 3.5 and the specific gravity is 4.5 to 5.

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Greenockite occurs with other sulfide minerals such as sphalerite and galena. It is the only ore mineral of cadmium, most cadmium is recovered as a byproduct of zinc and lead mining.

It was first recognized in 1840 in Bishopton, Scotland, during the cutting of a tunnel for the Glasgow, Paisley and Greenock Railway. The mineral was named after the land owner Lord Greenock. It is also known from the lead-zinc districts of the central United States.

References

• Mindat
• Webmineral
• Mineral galleries
• Glasgow museum site