Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have characteristic 34S values from lakes believed to be dominated by watershed sources of sulfate. The radioactive sulfur-35 is formed in cosmic ray spallation of the atmospheric 40Ar. This fact may be used for proving the presence of recent (not more than 1 year) atmospheric sediments in various things. This isotope may be obtained artificially by different ways. In practice, a reaction 35Cl + n → 35S + p, that runs at irradiation potassium chloride by neutrons, is used. The isotope sulfur-35 is used in various sulfur-containing compounds as a radioactive tracer for many biological studies, for example it was used in the Hershey-Chase experiment. Working with the compounds containing this isotope is relatively safe, under condition of not falling those compounds inside an organism of an experimenter. Natural occurrence 32S is created inside massive stars, at a depth where the temperature exceeds 2.5×109 K, by the fusion of one nucleus of silicon plus one nucleus of helium. As this nuclear reaction is part of the alpha process that produces elements in abundance, sulfur is the 10th most common element in the universe. Sulfur, usually as sulfide, is present in many types of meteorites. Ordinary chondrites contain on average 2.1% sulfur, and carbonaceous chondrites may contain as much as 6.6%. It is normally present as troilite (FeS), but there are exceptions, with carbonaceous chondrites containing free sulfur, sulfates and other sulfur compounds. The distinctive colors of Jupiter's volcanic moon Io are attributed to various forms of molten, solid, and gaseous sulfur. It is the fifth most common element by mass in the Earth. Elemental sulfur can be found near hot springs and volcanic regions in many parts of the world, especially along the Pacific Ring of Fire; such volcanic deposits are currently mined in Indonesia, Chile, and Japan. These deposits are polycrystalline, with the largest documented single crystal measuring 22×16×11 cm. Historically, Sicily was a major source of sulfur in the Industrial Revolution. Lakes of molten sulfur up to ~200 m in diameter have been found on the sea floor, associated with submarine volcanoes, at depths where the boiling point of water is higher than the melting point of sulfur. Native sulfur is synthesised by anaerobic bacteria acting on sulfate minerals such as gypsum in salt domes. Significant deposits in salt domes occur along the