The La Grasta Mine (“pirrera Grasta” in the local dialect) was active for over a century and a half, starting from the opening of its first tunnels in 1839, when the Upper Miocene veins attracted entrepreneurs from all over the island. Within a few years, extraction towers, Gill furnaces, and the humble lodgings of the carusi—young boys who descended as deep as 150 meters carrying thirty-kilogram sacks on their backs—appeared. On November 27, 1863, a cloudburst turned the valley into a whirlpool of water, flooding the tunnels and killing thirty-five miners: a tragedy that still lives on in songs dedicated to Saint Barbara, patron saint of the sulphur workers.
In the 1920s, the Ferrara company installed electric winches and ventilators, making La Grasta one of the most modern plants in the area. The purity of its deposit, enriched with delicate blue celestine crystals sought after by mineral collectors, made the mine strategic for the production of fertilizers, glass, and explosives destined for European markets. Decline came in 1987, crushed by competition from sulphur extracted through the Frasch process and by the energy crisis: machinery, rail tracks, and the great furnace chimney were left outdoors, prey to the wind and vegetation.