Sulphur,
Formula S.

Crystal system: Orthorhombic
Hardness: 1.5 to 2.5
Density: 2.1 gms/cm³
Colour: Yellow, sometimes brownish, greenish or reddish.
Streak: White

Sulphur is deposited as a sublimation product from volcanoes. It can also occur when sulphides such as pyrite are subjected to great heat. The largest deposits are found in the USA, Spain and Italy. Sulphur is extensively used in industry to make insecticides and fertilisers, and to produce sulphuric acid. About half of the sulphur used comes from native sulphur deposits; the rest comes from ores.

The specimen in the picture, of Sulphur crystals on Aragonite, came from Girgenti, Sicily, Italy.