This property is thought to be due to the formation of long polymeric chains of sulfur molecules. It burns in air with a blue flame, forming sulfur dioxide, SO2. Natural Occurrence and Processing Sulfur is widely distributed in nature. It is found in many minerals and ores, e.g., iron pyrites, galena, cinnabar, zinc blende, gypsum, barite, and epsom salts and in mineral springs and other waters. It is found uncombined in some volcanic regions and in large underground deposits in Sicily and in the United States in Texas and Louisiana.
Sulfur often occurs with coal, petroleum, and natural gas and has been found in meteorites.
It is found in plants and animals, being an element of most proteins and protoplasm. Sulfur is produced chiefly by the Frasch process , although it is also produced by the Sicilian method and by other methods. In the Sicilian method the sulfur-bearing ores are piled in a mound and ignited. The heat produced by the burning melts some of the sulfur, which is collected and cast. This sulfur is impure and is usually purified by sublimation.