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Iron mines

Iron mines
The geological knowledge of the territory have improved considerably in recent decades, thanks to the advent of geo-techniques and to the computer systems applied to survey techniques, used by the experts of earth sciences. A strong contribution to the knowledge of the area was made by technicians that dealt with mining geo-resources. Since prehistoric times, man always searched for minerals in the territory. In the territory of Monteleone there are settlements dating back to the Protohistoric period and surely the inhabitants of that time went in search of resources that this area offered them. The iron mines of Monteleone have been used for the mineral extraction that could be wrought since historical times; their discovery is crucial for the reconstruction of the anthrop passage of the Alta Valle del Corno. Among the raw materials on the national territory, the iron has had considerable use and development over time, to the point that in the last century the scientific research and hence the mining activities have concentrated on those fields that meet the needs of the economic development.

The Monteleone local deposits are of two different types: a) residual deposits and b) hydrothermal deposits.

a) The areas of Gavelli, Monte Cornuvolo, Rescia, Ocre and Colle Policiano are residual deposits, characterized by karst plans and sinkholes. The extraction of the ore was done open air, usually these deposits are found on the fund of the depressions of karst origin (called sinkholes often with pools of water with the formation of the so-called “wetlands iron”) or karst-tectonic origin (karst plains) and the oxides and hydroxides of iron with manganese oxides were separated from the gangue (waste material that must be removed from the ore before being used).

b) The mine, located in Terargo, on the South-eastern flank of Birbone Mount, is a hydrothermal deposit and it was also affected by underground mining. The mineral is located in correspondence of a fracture of tectonic origin. The mine is developed in a series of tunnels and passages within a very fractured limestone; in fact, it is located a fault that links the rock types of the Massif Limestone of Lower Jurassic with the  Jasper limestone of the Upper Jurassic. From an analysis carried out in 1940 in the laboratories of the National Research Council of Rome, the mined ore had the following composition: insoluble residue 23,20 - iron 57,60 (equal to 40.32% Fe) - Manganese 5.60 (4.03% Mn). The iron came from the mines of Birbone Mount, with which the two lateral gates of St. Peter's Basilica were made, (called of Urban VIII) and those that closed the Pantheon in Rome, removed in 1882 and transported to the Abbey of Casamari. On these artifacts there is an engraving with the following inscription: "Ex fundinis Montis Leonis", which certifies the provenance of the material being processed. Birbone Mount mines are still today easily reached by the paths of CAI.