Active from the late 1950s, the mine specialized in the extraction of kainite, an evaporitic mineral consisting of a hydrated double sulfate of potassium and magnesium, typically associated with rock salt. It is essential for the production of potassium sulfate, a fertilizer in high demand in agriculture. This type of activity, together with other mines extracting sulfur, made the Nisseno area one of the most important mining centers in Europe until the second half of the last century. The mining method adopted at Bosco – San Cataldo Section was the room and pillar system, leaving access routes at least 5 meters wide. The mine was equipped with a technologically advanced flotation plant, which allowed the separation of enriched kainite from rock salt.
At the peak of its activity, the site employed hundreds of workers and included an actual residential village with services and social spaces, making it a true social microcosm. The progressive depletion of the richest veins and the high extraction costs led to its definitive closure at Christmas in 1985, leaving a major occupational and social void in the area. Still remembered today is the cableway, 18 kilometers long, which transported enriched kainite to the Casteltermini plant for the preparation of potassium sulfate ready for commercialization. Unfortunately, the cableway was dismantled in the first half of the year following the closure, leaving on the ground one pylon lying at the edge of the waste basin – the so-called salt mountain – and another still standing in the middle of what remains of the pond that supplied the Casteltermini plant.
Today, although not open to visitors, the Bosco Mine – San Cataldo Section continues to be a historical reference point for the memory of Sicilian mining labor. In 2024, the Sicilian Region approved a site recovery project, which includes land reclamation, the removal of the waste basin (to be reused as anti-ice material for roads), the construction of a photovoltaic plant, and the planting of plant species resistant to saline soils.