ROCKS AND MINERALS

by Taya Morante

SULPHER

Discovery: Known since prehistoric time.

Properties: Sulfur has a melting point of 112.8°C (rhombic) or 119.0°C (monoclinic), boiling point of 444.674°C, specific gravity of 2.07 (rhombic) or 1.957 (monoclinic) at 20°C, with a valence of 2, 4, or 6. Sulfur is a pale yellow, brittle, odorless solid. It is insoluble in water, but soluble in carbon disulfide. Multiple allotropes of sulfur are known.

Uses: Sulfur is a component of gunpowder. It is used in the vulcanization of rubber. Sulfur has applications as a fungicide, fumigant, and in the making of fertilizers. It is used to make sulfuric acid. Sulfur is used in the making of several types of paper and as a bleaching agent. Elemental sulfur is used as an electrical insulator. The organic compounds of sulfur have many uses. Sulfur is an element that is essential for life. However, sulfur compounds can be highly toxic. For example, small amounts of hydrogen sulfide can be metabolized, but higher concentrations can quickly cause death from respiratory paralysis. Hydrogen sulfide quickly deadens the sense of smell. Sulfur dioxide is an important atmospheric pollutant.

Sources: Sulfur is found in meteorites and native in proximity to hot springs and volcanoes. It is found in many minerals, including galena, iron pyrite, sphalerite, stibnite, cinnabar, Epsom salts, gypsum, celestite, and barite. Sulfur also occurs in petroleum crude oil and natural gas. The Frasch process may be used to obtain sulfur commercially. In this process, heated water is forced into wells sunk into salt domes in order to melt the sulfur. The water is then brought to the surface.