Aux origines des techniques minieres. L'exploitation d'un gisement filonien au Premier Age du fer.Les mines de Silter di Campolungo et de Baita Cludona di Fondo (Val Camonica, Alpes lombardes, Italie)

摘要

Val Camonica is well known for its large and exceptional quantity ofrock carvings, but it is also an area rich in metallic ores. Two groups ofmining works have been explored and are the subject of this paper. Themining areas of Silter di Campolungo and of Baita Cludona di Fondo arein Val Grigna, a small hanging valley of glacial origin. It lies in the terri-tories of the communities of Bienno and Collio. The mining area of ValTrompia to the east of Val Camonica can be reached through Val Grignaand the Goletto di Cluodona pass. The distance between the two groups ofmines of Silter di Campolungo to the north and Baita Cludona di Fondo tothe south is 2 km as the crow flies. The bedrock in the area is formed by asequence of siliceous sediments belonging to the Collio formation, lowerPermian in age. They are layers of massive sandstones and conglomerateswith a sandstone matrix of various thicknesses (from decimetres to metres).This formation is crossed by faults which are mineralized with 15-20 cmthick veins of chalcopyrite-bearing white epigenetic quartz. These twocopper mines, which have been dated to the Early Iron Age, were the sub-ject of archaeological exploration between 1997 and 2002. Their study hasshown some mining techniques previously unknown for that age. The miningactivity at Campolungo begun as an opencast mine with the excavation ofdeep trenches where the ore was visible on the surface. These works beginat 1535 m above sea level and reach an attitude of 1635 m. At 1535 m thereis the opening of the drainage adit while the higher altitude correspondsto the last of the opencast works. In order to reach the deepest copper lodesof Campolungo the ancient miners dug an adit about 120 m long.