Greenockite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameGreenockite
Chemical FormulaCdS
Mohs Hardness3
Crystal Systemhexagonal
Lusterresinous
Streak Colororange-yellow
Cleavageperfect on {0001}
Fractureconchoidal
Specific Gravity4.5
Colorsyellow, orange-yellow, brownish-yellow, reddish-brown
Transparencytransparent
Type LocalitySiglo Veinte Mine (Siglo XX Mine; Llallagua Mine; Catavi), Llallagua, Rafael Bustillo Province, Bolivia
Mineral GroupSulfides
Usesminor ore of cadmium, collector
Associated Mineralscassiterite, sphalerite, galena, pyrite, chalcopyrite, quartz, calcite, barite
Rarityuncommon
Description
Greenockite typically forms small, bright yellow to orange-yellow, often pyramidal or tabular crystals, sometimes as coatings or earthy masses. In this image, it appears as vibrant orange-yellow crystals coating a darker matrix, likely cassiterite.
Geological Context
Greenockite is a rare secondary mineral found in zinc and lead ore deposits, often associated with sphalerite and other sulfide minerals. It forms in hydrothermal veins or as an alteration product of cadmium-bearing minerals.
