Sulphur deposits in the Krafla lava field, Iceland. The Krafla eruption of 1975 began near Myvatn and Namafjall. This place is a well known as part of the active volcanic zone of Iceland. Sulphur is a chemical element (symbol S) which occurs in two forms, but in Iceland, only elemental sulphur is found. Solfatares, openings in the Earth's crust, emit hydrogen sulphide (and other gasses) which, in contact with oxygen, turn into elemental sulphur and sulphur dioxide. It was mined in parts of Iceland since the middle ages for the manufacture of gunpowder and only ceased production in the 19th century.