Near surface geothermal alteration and associated weathered volcanic rocks concentrate a number of industrial minerals. New Zealand mineral companies mine active and fossil geothermal systems for a variety of raw materials including: colloidal silica, clay (Halloysite and Kaolinite), pumice, zeolite, perlite, and native sulphur.
Geothermal fluids also carry potentially valuable minerals such as lithium (for batteries) and amorphous silica (for semiconductors). Over the years several parties have conducted experimental extraction trials but none to date have proven economic. Currently the GEO40 company operates a pilot plant at Ohaaki for extracting ultra-fine silica for export markets http://geo40.com