Smithsonite
A zinc carbonate mineral named after James Smithson.
Smithsonite, also known as zinc spar, is the mineral form of zinc carbonate (ZnCO3). It was historically identified with hemimorphite before being recognized as a distinct mineral, leading to confusion under the term calamine.
- type
- mineral
- chemical_formula
- ZnCO3
- mohs_hardness
- 4.5
- specific_gravity
- 4.4 to 4.5
- crystal_system
- trigonal
- named_after
- James Smithson
Lore & Background
Smithsonite is a variably colored trigonal mineral that only rarely forms well-shaped crystals, typically occurring as earthy botryoidal masses. It has a Mohs hardness of 4.5 and a specific gravity of 4.4 to 4.5. The mineral occurs as a secondary mineral in the weathering or oxidation zone of zinc-bearing ore deposits and sometimes as replacement bodies in carbonate rocks, constituting zinc ore.
Reader's Guide
Smithsonite's significance lies in its historical confusion with hemimorphite, both being called calamine, and its naming after James Smithson, the founder of the Smithsonian Institution. It forms limited solid solution series with rhodochrosite (manganese substitution) and siderite (iron substitution). A bright yellow variety, known as 'turkey fat ore,' owes its color to greenockite inclusions. Smithsonite commonly associates with hemimorphite, willemite, hydrozincite, cerussite, malachite, azurite, aurichalcite, and anglesite.
Did You Know?
- A bright yellow variety is called 'turkey fat ore' due to greenockite inclusions.
- Smithsonite forms limited solid solution series with rhodochrosite and siderite.
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