Sulphur

Sulphur forms bipyramidal crystals with a colour varying from citrine yellow, when the mineral is pure, to yellowish brown, to almost black if made impure by the presence of bitumen. There is no lack, however, of cases in which it is found in the form of compact, granular, earthy and stalactitic aggregates. It is very light, brittle, electrostatic and fusible at low temperatures (119 °C), with the emission of sulphur dioxide.

It generally forms in sedimentary rocks of evaporitic type, thanks to the biological activity of certain species of bacteria.

Being the most important sulphur mineral, it is mainly used for the production of sulphuric acid and other compounds.