“Black smokers,” represented in this illustration, spew hot fluid (360°C) filled with metals (mostly iron) and sulfur, which combine to form black minerals called metal sulfides. These compounds give the smoker its black color.

“White smokers” generally are smaller, release fluid more slowly, and are cooler (250° – 300°C) than their cousins. The fluid contains compounds of barium, calcium, and silicon, which are white.

Copyright University of Delaware.