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TITLE: Black Smokers—Undersea Oases


[Photo: Black smoker]

Discovered in 1979, black smokers are the hot springs of the deep sea. At the Juan de Fuca Ridge, they have built spectacular chimneys up to 14 stories tall. Black smokers support ecosystems of unique lifeforms. The smokers eject sulfides that feed bacteria at the bottom of an unusual food chain that exists only in the inky blackness of the ocean floor.

 

 





Seawater descends through fractures in the oceanic crust flanking spreading ridges. Magma heats the water to temperatures as high as 350° C (660° F).

  [Photo: Hot mineral "soup" and Depleted Basalt]

The heated water dissolves sulfur, copper, iron, manganese, cobalt, nickel, and other elements from sea-floor basalt. This rich, hot "soup" rises through vents.

  [Photo: Cold seawater and Black smoker]

As the hot water mixes with cold seawater, dissolved elements precipitate. Crystals of iron-, copper-, and zinc-sulfides, along with calcium sulfate, billow upward.

 

  [Photo: Crystal-laden "smoke"]

  Photo: Sulfide and Barite Chimney  
  Sulfide and
Barite Chimney
 

Crystals accumulate around the vents to form chimneys.

 

  [Photo: Chimney]

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Smithsonian National Museum of Natural History Department of Mineral Sciences website Credits