Hydrothermal brines in the Salton Trough in southern California contain over 100 million metric tons of dissolved Fe-Mn-Zn-Pb-Cu, that likely came from adjacent rocks. Dr. Mike McKibben, geochemistry prof at UC Riverside told a big crowd at last night's Arizona Geological Society dinner meeting that "these tonnages are comparable to the largest massive sulfide orebodies ever mined from ancient sediment-hosted rift settings." [right, model of magmatic addition to the crust from Schmitt & Vazquez (2006), as a model for the Salton Trough].
Mike made the case that similar continental rift environments may be the source for other, large mineral deposits. He called the hot subsurface brines, "liquid ore bodies."
He also recounted CalEnergy's $300 million expenditures in a failed attempt to produce zinc from the hydrothermal brines associated with their geothermal power plant. The problems occurred in scaling up bench tests to full production mode without understanding the hydrometallurgy. He thinks a new project to produce lithium commercially from the brines has a much better chance of success and could produce 25% of the world's lithium demands.