On 19th July 1985, a mineral waste facility made up of two tailings dams collapsed in the Stava valley (Municipality of Tesero, Province of Trento, Italian Alps). This facility served a fluorite mine and was raised over a period of more than 20 years in order to decant, consolidate and store the tailings resulting from the froth flotation process of the Prestavèl mine and other fluorite mines of Trentino, South Tyrol and Lombardy.