AbstractAntimony and arsenic are commonly mobilised into the environment from mesothermal mineral deposits. Both these metalloids are potentially toxic in the environment when dissolved in water at low levels (<0·01 mg/l). Mobility of antimony, in comparison to that of arsenic, is documented at mine sites in four different mesothermal systems in low grade Palaeozoic-Mesozoic metamorphic terranes of New Zealand (Globe Hill, Reefton; Macraes, Otago; and Endeavour Inlet, Marlborough) and Australia (Hillgrove, New South Wales). Dissolved antimony can reach ~50 mg/kg in mine waters where evaporative concentration occurs in oxidised near-neutral pH mine waters in contact with stibnite. Such waters are chemically saturated with respect to antimony oxides, and antimony oxide precipitation occurs locally. Most mine waters have lower dissolved Sb concentrations, especially where high rainfall causes dilution. However, high rainfall areas have widespread diffuse mobilisation of both Sb and As to give elevated backgr...