Hydrothermal Vents Black smokers lots of sulfur minerals that make dark plume.Chimney made of calcium sulfate and metal sulfides. White smokers barium,calcium and silicon precipitates form white plume.Chimneys made of calcium carbonate.Lost City in the Mid-Atlantic Ridge produces white smokers.Reactions between seawater and upper mantle peridotite produce methane-and hydrogen-rich fluids that are highly alkaline(pH 9 to 11),with temperatures ranging from<40°to90°C.Hydrothermal Vents • Black smokers - lots of sulfur minerals that make dark plume. Chimney made of calcium sulfate and metal sulfides. • White smokers - barium, calcium and silicon precipitates form white plume. Chimneys made of calcium carbonate. Lost City in the Mid-Atlantic Ridge produces white smokers. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids that are highly alkaline (pH 9 to 11), with temperatures ranging from <40° to 90°C