Exploitation of the Traversella Mine in the 18th and 19th centuries

Traversella mine is located around 50 km north of Turin, and it was one of the most important extraction site for iron exploitation. The Traversella orebody was exploited from late medieval age up to the middle of the XX century. It is a characteristic contact-metasomatic deposit at the contact between granodiorite and preexisting enclosing rocks ( crystalline schist of the “Sesia-Lanzo” Massif). The mineral extracted from different veins and mass in the contact aureola was primarily magnetite, an iron oxide easy to treat in cast iron employing the technology locally available before 1900. Only after the beginning of XX century the extraction involved also pyrite and chalcopyrite (iron and copper-iron sulfide) useful for the production of sulfuric acid. The mine, after some interruption and re-opening, was officially closed in the second half of the XX century, due to the excessive extraction costs and the competition with mine deposits abroad. The mine was one of the main resources for a population that lived in a very poor background, a small alpine valley in the northwest of Piedmont. The locals usually worked at the mine during winter, only when farming activities were not possible. The period between XVIII and XIX century is very important from an historical point of view, because documentary evidence is still existing and it is possible to reconstruct the production of the mine during this time lapse, and it is also possible to distinguish year by year the single contribution of each claim owners. Analysis of available data in such period shows the existence of two production peaks, at the end of the XVIII century and during 1830. It also shows the decrease of the mineral productivity at the end of XIX century, when the mine remained closed for a long period. It is very interesting to highlight the sequence of families that conducted the mine works during the decades. In these years the small mining concessions of early times evolved in more complex and bigger claims, as a consequence of a more efficient organization and of an acquisition policy of mining licenses by few owners. Documental reports show the internal contrast between single owners, local administration and central government, about the imposed duties and taxes; This communication describes some results achieved by the team of the “Research Project PROactive management of GEOlogical heritage in the PIEMONTE region”, a three-years project of the University of Turin funded by the , regarding the sub-theme “Brosso e Traversella”.