The antique Lovignanaz mine (also known as Molina mine) is located in the western side of the Clavalité valley (1350-1425 m a.s.l.), to the South of the Fénis village, in the southern side of the Aosta Valley (Italy). The mine galleries are developed within chloriteschists, talcschists and metagabbros transposed with calcschists belonging to the Piedmont nappe (Zermatt-Saas zone). The rocks hosting the Fe-Cu sulphide mineralization show blueschist to eclogite facies mineral associations like those studied in Saint-Marcel rocks (Martin et al., 2008, and ref. therein). The mineralization is characterized by disseminated chalcopyrite and pyrite associated with minor ilmenite, rutile, pyrrhotite and magnetite (Fénis. Une communauté au fil de l'histoire, 2000 and ref. therein). The oldest galleries were dug with techniques described by Agricola in De Re Metallica (1556) and have been attributed to the Romans. These techniques consist in excavation along mineralized layers after “fire-setting”, that is after weakening the rocks with a fire (De Re Metallica, book V). Other galleries have been excavated with more recent techniques, revealing the use of explosives, and have been attributed to XVIII-XIX centuries mining activity (Gerbore E. E., in: Fénis…, op. cit.). The remnants of a furnace for rock-roasting have been found along the right side of the Clavalité river (lat. N 45° 41’ 46’’; long. E 7° 29’ 51’’). In the same site, slags with charcoal and red burnt soil, probably related to an old activity, were observed during the field work. Several glassy slags, maybe produced during XVIII-XIX centuries mining activity, were found below a large landslide that partly covers the mine adits. Near the oldest mine entrances traces of old working instrument have been found. These mines were also used to extract millstones: few metres from the mine entrances in the Mouilé locality (Fénis…, op. cit.), some of these stones are still unexcavated on the rock walls. In the lower part of the valley, in correspondence of Miserègne village (Fénis), there is a dump where many large slags with charcoal fragments are piled up. Some of these fragments were analyzed with 14C method and one of them has been dated to IV century b.C.. This age is the oldest found for charcoal associated to slags of the Cu mines in the Aosta Valley. Other slags from the Saint Marcel valley yielded early medieval ages (Tumiati et al., 2005). The Lovignanaz mining site has been destroyed by landslide events, the last one having occurred in 2000, which partly covered mine entrances and other structures linked to mining activity. The presence of structural lineaments and the practice of “fire-setting” during mining activity may have contributed to trigger the landslide.
The Lovignanaz Cu-Fe-sulphide mine: safeguard of a pre-Roman mining site
GIANOTTI, FRANCO;
2011-01-01
Abstract
The antique Lovignanaz mine (also known as Molina mine) is located in the western side of the Clavalité valley (1350-1425 m a.s.l.), to the South of the Fénis village, in the southern side of the Aosta Valley (Italy). The mine galleries are developed within chloriteschists, talcschists and metagabbros transposed with calcschists belonging to the Piedmont nappe (Zermatt-Saas zone). The rocks hosting the Fe-Cu sulphide mineralization show blueschist to eclogite facies mineral associations like those studied in Saint-Marcel rocks (Martin et al., 2008, and ref. therein). The mineralization is characterized by disseminated chalcopyrite and pyrite associated with minor ilmenite, rutile, pyrrhotite and magnetite (Fénis. Une communauté au fil de l'histoire, 2000 and ref. therein). The oldest galleries were dug with techniques described by Agricola in De Re Metallica (1556) and have been attributed to the Romans. These techniques consist in excavation along mineralized layers after “fire-setting”, that is after weakening the rocks with a fire (De Re Metallica, book V). Other galleries have been excavated with more recent techniques, revealing the use of explosives, and have been attributed to XVIII-XIX centuries mining activity (Gerbore E. E., in: Fénis…, op. cit.). The remnants of a furnace for rock-roasting have been found along the right side of the Clavalité river (lat. N 45° 41’ 46’’; long. E 7° 29’ 51’’). In the same site, slags with charcoal and red burnt soil, probably related to an old activity, were observed during the field work. Several glassy slags, maybe produced during XVIII-XIX centuries mining activity, were found below a large landslide that partly covers the mine adits. Near the oldest mine entrances traces of old working instrument have been found. These mines were also used to extract millstones: few metres from the mine entrances in the Mouilé locality (Fénis…, op. cit.), some of these stones are still unexcavated on the rock walls. In the lower part of the valley, in correspondence of Miserègne village (Fénis), there is a dump where many large slags with charcoal fragments are piled up. Some of these fragments were analyzed with 14C method and one of them has been dated to IV century b.C.. This age is the oldest found for charcoal associated to slags of the Cu mines in the Aosta Valley. Other slags from the Saint Marcel valley yielded early medieval ages (Tumiati et al., 2005). The Lovignanaz mining site has been destroyed by landslide events, the last one having occurred in 2000, which partly covered mine entrances and other structures linked to mining activity. The presence of structural lineaments and the practice of “fire-setting” during mining activity may have contributed to trigger the landslide.
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