In some areas of the canton (Val Morobbia, Val Colla, Valle di Isone and Malcantone), deposits of minerals used for the production of iron have been found. However, local extraction has never been sufficient to be economically relevant, and it was often necessary to resort to importing metal from Italy for the production of objects. In these areas, from 1400 onwards, various mining and steel companies have taken turns, such as the Bruni company of Bellinzona, and the Airoldi and Bianchi companies of Lugano. In 1900, metallurgy and steel industry became one of the main branches of the manufacturing sector with companies such as Monteforno SA of Giornico-Bodio, which in the 1970s was the main industrial company in Ticino.