In the Waiotapu geothermal area only Champagne Pool, 109
ng/L, and Waiotapu Geyser, 7.6 ng/L, have dissolved Au concentrations greater
than 5 ng/L and most springs have concentrations less than 2 ng/L. When Au
concentration data are combined with other physico-chemical data from each
spring including; pH, reduced sulphur concentration and temperature, the degree
of Au saturation can be calculated. All samples sites except Champagne Pool,
Waiotapu Geyser and the Artists Palette are under-saturated with respect to
Au(s) by 1 to 3 orders of magnitude. This indicates that adsorption or
co-precipitation or both are important processes depositing Au beneath hot
springs. Deposition of Au by adsorption or co-precipitation beneath
hot springs
implies that dissolved Au may not have to reach saturation concentrations for
ore to deposit. This interpretation is supported by the presence of substantial
Au as sub-microscopic components within sulphide minerals in ore deposits and
indicates depositional efficiency beyond that possible through precipitation of
Au(s).