Cadmian Smithsonite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameCadmian Smithsonite
Chemical Formula(Zn,Cd)CO₃
Mohs Hardness4.5
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavageperfect rhombohedral {1011}
Fractureuneven
Specific Gravity4.4
Colorsyellowish-brown, golden-brown
Transparencytranslucent
Type LocalityTsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto (Oshikoto) Region, Namibia
Mineral GroupCarbonates
Usescollector, minor ore of zinc
Associated Mineralshemimorphite, cerussite, anglesite, malachite, azurite, calcite
Rarityuncommon
Description
This specimen features a dense crust of small, yellowish-brown to golden-brown rhombohedral crystals, exhibiting a vitreous to sub-adamantine luster. The crystals form a sparkling, botryoidal-like aggregate on a matrix.
Geological Context
Smithsonite is a secondary mineral formed in the oxidized zones of zinc-rich ore deposits, typically resulting from the alteration of primary zinc sulfides such as sphalerite. Cadmian smithsonite indicates the presence of cadmium substituting for zinc during its formation in such environments.
