Sicily’s sulfur deposits lie across the chalky–sulfur plateau between Caltanissetta, Enna, and Agrigento provinces and were mined as early as 200 BCE by the Romans; following a new mining process in 1787, large-scale extraction began. By the late 19th century Sicily produced roughly 90 percent of the world’s sulfur from open pits and underground mines like Cozzo Disi, Lercara Friddi, and Grottacalda. The advent of a new mining process in the early 20th century made Sicilian ore uncompetitive, leading to most mines closing by the 1970s . Today, many former mine sites serve as geo-heritage museums (e.g., the Cozzo Disi mine-museum) and collectors prize well-formed orthorhombic sulfur crystals such as this.