US and New Zealand researchers recently found massive gold and silver deposits in reservoirs underneath a volcanic range on New Zealand. Project researcher Stuart Simmons told Quartz that find could be worth between $50 million and $250 million, though that is speculation. As Simmons explains:
Taupo Zone [is]…similar to Yellowstone National Park in the US, volcanic magma enriches underground water with heat, chemicals, and in some instances, precious metals.The steam from the area’s hot springs is used as a source of geothermal energy, Simmons explained, and when the hot water moves toward the earth’s surface, it is sometimes caught in the pipes of geothermal production wells—which are designed to generate power from hot water in the earth. Over time, thin films of silver and gold build in the pipes of these wells.