Hydrothermal circulation
Videos
Hydrothermal circulation in its most general sense is the circulation of hot water. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust. In general,
Taal Volcano Main Crater Lake, where hydrothermal circulating convection cells exist
Ore genesis
Videos
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz-gold vein in California's Mother Lode. Specimen is 3.2 cm (1.3 in) wide.
High-grade (bonanza) gold ore, brecciated quartz-adularia rhyolite. Field of view ~10.5 cm across. Native gold (Au) occurs in this rock as colloform bands, partially replaces breccia clasts, and is also disseminated in the matrix. Published research indicates that Sleeper Mine rocks represent an ancient epithermal gold deposit (hot springs gold deposit), formed by volcanism during Basin & Range extensional tectonics. Sleeper Gold Mine, Humboldt County, Nevada.
Citrobacter species can have concentrations of uranium in their bodies 300 times higher than in the surrounding environment.
Tunicates such as this bluebell tunicate contain vanadium as vanabin.