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 % ZnCO3and 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.