Former lead and zinc mine at Cave del Predil, converted into an accessible geomining heritage park with guided underground tours.
The Pozzo Clara forms part of the Parco Internazionale Geominerario di Raibl at Cave del Predil, the former lead and zinc mining complex in the Friuli Venezia Giulia Alps, situated ten kilometres south of Tarvisio in the province of Udine. Known historically as the Miniera di Raibl, the site exploited lead and zinc ores — primarily sphalerite (blenda) and galena — in Triassic dolomitic limestones of the Monte Re massif. Documentary evidence of extraction dates to 1320, when Duke Frederick of Habsburg granted a mining concession to a consortium of local miners.
The mine grew through phases of Habsburg state and private ownership and became one of the most important lead and zinc mines in Europe. Pozzo Clara served as a principal extraction shaft; in 1898 the first hydroelectric power station at Cave del Predil was constructed specifically to supply electricity to the winding engine of Pozzo Clara. At its peak in the 1940s and 1950s the mine employed 1,148 workers.
The underground system eventually comprised more than 130 kilometres of galleries distributed across 19 levels, reaching 520 metres below the level of the village. The mine closed on 30 June 1991, not due to ore exhaustion — reserves of over 3 million tonnes had been confirmed — but because extraction could not compete economically with imported metals. Following closure, the site was converted into the Parco Internazionale Geominerario, an educational and heritage ecomuseum offering guided tours by electric train through some 1,200 metres of accessible galleries.
The locality of Cave del Predil, situated at 900 metres above sea level between Monte Re, Monte Cinque Punte, and the Lago di Raibl in the Valcanale, owes its existence entirely to the mining of lead and zinc from the adjacent Monte Re. Exploitation of the ore deposits is believed to date from pre-Roman times; the mineral veins were worked in Phoenician and Roman antiquity. The first written documentary evidence is a concession granted in 1320 by Duke Frederick I of Habsburg to a consortium of miners in the Tarvisio area.
The deposits consist principally of sulphide mineralisation — sphalerite, galena, pyrite, and marcasite — in a gangue of dolomite, calcite, and baryte, in Triassic dolomitic limestones at contact with Upper Permian limestones. Through the medieval and early modern period the mine operated with varying fortunes under both public and private management. In 1456 the Bishop of Bamberg granted Osvaldo Raibl the right of extraction; for many centuries thereafter the mine was administered by the Rechbach family.
In 1759 Raibl and its mine passed into the possession of the Habsburgs. Towards the end of the eighteenth century, one portion of the mine came under direct Imperial government management — designated Raibl I — employing 186 workers within a year and developing industrialised extraction methods. The private portion, designated Raibl II, continued in separate management successively under the Struggl family, the Schnablegger family, and then the counts Henckel von Donnersmarck, who purchased the private portion in 1871.
In 1883 the population of Cave del Predil stood at 479 inhabitants, with miners commuting from surrounding villages. At the close of the nineteenth century the mine was enriched by technological transformation. In 1898 the first hydroelectric power station was constructed at Cave del Predil — powered by the local watercourse — specifically to supply electricity to the winding engine of the principal extraction shaft, Pozzo Clara; the village of Cave del Predil was among the first in the region to benefit from domestic electric lighting as a consequence.
In January 1910 a mining disaster occurred when a gallery wall collapsed and water from the overlying lake penetrated the mine, causing the village hospital to subside and sink and killing seven people. A monument was erected to commemorate the victims. During the First World War, the mine's principal long drainage gallery — 4,877 metres in length, excavated in the late nineteenth century to drain the deepest working levels at 240 metres below the village level, and crossing into what is now Slovenian territory — was converted into a military transit route.
In 1917 it was equipped with a narrow-gauge railway capable of transporting 170 tonnes of material and 600 soldiers per day, permitting Austro-Hungarian forces to move unseen toward the front at Caporetto. In the weeks before the Battle of Caporetto, approximately 270,000 troops and 22,000 train movements passed through the gallery. Following the First World War, the Treaties of Saint-Germain and Rapallo transferred the Tarvisio area, including the mine, to Italy.
The historic toponym Raibl was Italianised as Cave del Predil. In the post-war period, the mine was reorganised under the Società Anonima Miniere Cave del Predil. Operations intensified through the interwar period and reached their workforce peak in the 1940s and 1950s, when 1,148 employees were engaged and the gallery network had extended to over 110 kilometres.
From 1953 a period of crisis set in. The Società Mineraria del Predil (Raibl), successor to the post-war company, transferred management to the Società Mineraria Metallurgica di Pertusola in 1956. In 1963 the concession passed to the Azienda Mineraria Metallurgica Italiana S.p.A. (AMMI), a state-controlled company.
In 1965 the Regione Friuli Venezia Giulia became the owner of the mine. In 1979 management of the deposit was delegated to Samim S.p.A. (Società italiana miniere), a company within the ENI group. A 1988 operating convention was extended to 30 June 1991.
By the end of operations, the underground system comprised more than 130 kilometres of horizontal galleries distributed across 19 levels descending to 520 metres below the level of the village, and over 150 kilometres of total gallery if all developments are included. The mine was confirmed to hold proven reserves in excess of 3 million tonnes of ore at closure. Despite these reserves, the Regione Friuli Venezia Giulia and ENI (the effective manager through Samim) declared the mine uneconomical given competition from imported metals.
In January 1991 it was announced that the Region would not renew the concession beyond June 1991. Miners occupied Pozzo Clara for 17 days in protest, but an agreement signed on 22 February 1991 — providing for environmental remediation, museum conversion of parts of the gallery system, and an industrial metallurgical facility managed by Gruppo Cividale — ended the occupation. The mine closed on 30 June 1991.
Of the commitments made in the February 1991 agreement, the museum conversion was subsequently realised. The former mine became the Parco Internazionale Geominerario di Raibl, a publicly accessible heritage ecomuseum. The visitor circuit traverses 1,200 metres of accessible galleries by electric train, including working chambers, mineralised faults, the Camerone di Santa Barbara, and the Pozzo Layer with its winding gear still operational.
An associated documentary museum, the Miniera Lab, housed in the former mine offices building, and a military history museum were established in the same complex. The mine archive was preserved at the Archivio di Stato di Trieste under the designation Archivio Raibl — Società Mineraria del Predil. The closure of the mine marked a severe demographic crisis for Cave del Predil, with the population declining from 2,100 in 1968 to approximately 400.