Zincian dolomite from broken hill,New South Wales |
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Authors: | W. D. Birch |
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Affiliation: | Department of Mineralogy and Petrology , National Museum of Victoria , 285–321 Russell Street, Melbourne , Vic. , 3000 |
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Abstract: | Many Broken Hill (New South Wales) specimens labelled ‘zinco‐calcite’ in museum and private collections are snow‐white, globular forms with a sparkling appearance, on a coronadite or limonite matrix. X‐ray diffraction and microprobe analyses show the globules have a core of nearly pure calcite, overlain by colourless, drusy zincian dolomite with up to 4 mol % ZnCO3 and up to 7 mol % excess CaCO3. Although Zn is abundant in the Broken Hill orebody, it apparently entered carbonate, mainly as smithsonite, only during formation of the oxidised zone. |
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Keywords: | ‘lime‐zinc carbonate’ zinco‐calcite’ zincian dolomite magnesian smithsonite oxidised zone Broken Hill |
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