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Images: The Remarkable Diversity of Seafloor Vents

When hot hydrothermal fluid jets from the seafloor and mixes with cold seawater, fine particles of dark metal sulfides precipitate out of solution, creating the appearance of black “smoke.”

The Birth of a Black Smoker: The key to the creation of black smoker chimneysis an unusual chemical property of the mineral anhydrite, or calcium sulfate (CaSO4). Unlike most minerals, anhydrite dissolves at low temperatures and precipitates at high temperatures greater than ~150°C (302°F).

Cross Section of a Black Smoker Chimney: As hydrothermal fluid vents from the seafloor, different minerals in it precipitate at different temperatures, creating a multi-layered black smoker chimney.