A white, yellow, green, or blue mineral, formerly known as
calamine, consisting of zinc
carbonate (ZnCO3). Smithsonite occurs widely, an ore of zinc
formed by alteration of other zinc minerals and commonly associated with
galena, and calcite.
Its crystals, which are rare, are rhombohedral in the trigonal system; it
usually occurs in masses. Blue specimens from New Mexico have been used
as gemstones. It is named for the British chemist James Smithson,
after whom the Smithsonian Institution is also named. Hardness 4–4.5;
relative density 4.4.
|Smithsonite from Namibia.
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