Sulphur is a very common chemical element in nature. It can be found in its free state, in which case it is a clear citrine yellow colour, or combined with other elements such as limestone or gypsum which give it a brownish or light grey colour. It can be volcanic or sedimentary in origin: the deposits in the Agrigento area belong to the second type, i.e. they were created by the reduction of calcium sulphate (gypsum) or by the atmospheric alteration of metal sulphides.
In literature, this material is often found associated with the themes of hell.
