Distribution of critical elements in rocks and fluids, Taupo Volcanic Zone, New Zealand

Elements with the highest concentrations (>100kg/a) in the Taupo Volcanic Zone (TVZ) geothermal fluids, from lowest to highest, include Mo, Sb, Sr, W, Al, Cs, Rb, As, Li, Ca, B, Si and Na. Although discharge fluids produce only similar to 1-75 kg/a of Au, Ga, Tl, Ag, Ge, Rb and Cs, their high market prices warrant further study. Amongst gases of economic interest in the TVZ are CO2 mainly for food processing, C2H6 and He. It is estimated that one producing geothermal system has similar to NZ$850M/a worth of elements or similar to NZ$19.5B/a for 23 systems. However, despite the presence of a wide range of critical elements in the TVZ fluids, only a few can be economically and technologically extracted at present.