Sulfur is a native element that crystallizes in the rhombic system and has a low hardness (11/2-21/2) and a density of 2 g/cm3. It has a greasy or resinous shine and is characterized by its yellow colour, which can sometimes turn orange, greenish or brownish. Although more than 50 morphologies have been described, the most common is blocky dipyramidal, like the one shown in the photograph. You can also see reniform or stalactitic forms.

The Cáucaso mine in Conil de la Frontera is a classic deposit of sulfur crystals known since the 18th century. It is one of the first chemical elements known to man, and there are indications of work in the area probably since Roman times.

Sulfur is used to manufacture sulfuric acid, gunpowder, matches, fireworks, dyes, and in the vulcanization of rubber. It is also used as a solvent in agriculture, veterinary medicine and medicine.