The Element, Sulfur, like most elements lighter than iron, is believed to have been created by the nuclear fusion of lighter elements in the interior of stars. On Earth, it is widely distributed in its elemental state as a secondary mineral or as a volcanic deposit, as well as in combination with a number of metals. Large sedimentary deposits of the almost pure element, mainly of Tertiary age, are found in the coastal regions of Texas and Louisiana; on the Isthmus of Tehuantepec, Mexico; and in Sicily. Sulfur occurs in some fossil fuels, most notably coal, in chemical combination with carbon and other elements; its removal is difficult. Sulfur is prevalent in the sulfide ores of important metals: iron pyrite, sphalerite (zinc sulfide), and galena (lead sulfide). It is also found in calcium sulfate (gypsum) and barium sulfate (barite). The magnesium and sodium sulfates are present in ocean water and in many mineral waters. Sulfur occurs in living plant and animal tissue as part of the chemical makeup of the amino acids cysteine, cystine, and methionine. Organic sulfur compounds occur in garlic, mustard, onions, and cabbage and are responsible for the odor of skunks.