Hydrothermal
Definition
Relating to the action of hot water, especially in the Earth's crust. Many important mineral deposits form from hydrothermal solutions.
Example
Quartz and gold often precipitate from hydrothermal fluids circulating through rock fractures.
Nature's Hot Water Plumbing
Hydrothermal refers to geological processes involving hot water. Deep underground, water heated by magma circulates through cracks in the rock. This superheated water (often exceeding 300°C/572°F) can dissolve minerals that normal water cannot, such as gold, silica, and copper. As this mineral-rich soup moves into cooler areas or lower pressure zones, it can no longer hold the minerals in solution, so they precipitate out, forming veins.
Economic Importance
Most of the world's metallic ore deposits—including Gold, Silver, Copper, Lead, and Zinc—are hydrothermal in origin. Without this natural refining process, these metals would be too scattered in the crust to mine profitably. Gemstones like Emeralds and Quartz crystals also grow in these hot water cavities.