Surviving 47-metre concrete headframe and surface buildings of the Peñarroya lead, zinc and silver mine at Largentière, the largest modern lead mine in France.
The Mine de Montredon at Largentière, in the Ardèche department, was the principal modern extraction shaft of a lead, zinc, and silver deposit known since the medieval period and systematically exploited by the Société Minière et Métallurgique de Peñarroya from 1964 to 1983. Silver mining in the Largentière area is documented from at least the tenth century, when the argentiferous deposit gave the town its name and provided wealth for the bishops of Viviers, who used the silver to mint coins. Exploitation ceased around the end of the fourteenth century.
In the nineteenth century, fresh searches led to a brief revival of lead and silver extraction between 1875 and 1883. The modern exploitation began when Peñarroya launched a systematic prospecting campaign from 1952, completing it around 1960. The Montredon shaft was sunk starting in 1961 in the commune of Largentière, with a second shaft at Chassiers following in 1962.
Surface installations including the concrete headframe, ore processing building, laverie, and workshops were completed in 1964. At peak production the mine employed 153 people. Total output over the working life was approximately 9.6 million tonnes of ore, yielding 356,203 tonnes of lead, 68,569 tonnes of zinc, and 750 tonnes of silver.
Exploitation ended in 1983. After closure, around 800 kilometres of underground workings were flooded. The imposing 47-metre concrete headframe tower of the puits de Montredon, together with the surrounding processing buildings, remains standing today, as does partial workers' housing.
The former tailings pond at the Colombier site is now covered by a 24-hectare photovoltaic installation.
The Largentière lead deposit is a large stratiform accumulation of baryte and lead-zinc-silver ore hosted in Triassic sandstones in the valley of the Ligne, a tributary of the Ardèche, in the southern Cévennes piedmont. The deposit has been known and exploited in successive phases spanning more than a thousand years.
Medieval exploitation began no later than the tenth century, when the valley's silver resources gave rise to the town of Largentière — a name deriving from Argentaria. During the eleventh and twelfth centuries the silver mines were important enough for the bishops of Viviers to mint coins with their produce, and the rights over the deposit were contested between the bishops, the counts of Toulouse, and other powerful lords. A document of 1146 is the earliest textual reference specifically to these mines. Extraction appears to have ceased around the end of the fourteenth century, though substantial spoil heaps (haldes) persisted on the landscape for centuries. Archaeological surveys have established that extraction was active between the eleventh and fourteenth centuries in the valley of the Ligne.
No significant production is documented for several centuries after the medieval closure. In the nineteenth century the expansion of industrial demand stimulated new prospecting. A brief period of lead and silver extraction took place between 1875 and 1883, with ore processing conducted at a washing plant established on the right bank opposite the Sigalière. These works were abandoned in 1885 or shortly thereafter.
In 1952, the Société Minière et Métallurgique de Peñarroya — a major French mining company — initiated a systematic prospecting campaign at Largentière. Extensive drilling continued until approximately 1960, when the gisement was confirmed as economically exploitable. Infrastructure construction commenced in 1961 with the sinking of the puits de Montredon, located in the Montredon quarter approximately two kilometres east of Largentière towards Chassiers. A second shaft was sunk at Chassiers in 1962. The surface installations — including the concrete headframe, ore crushing and processing building, laverie, and workshops — were completed and commissioned in 1964, the year in which full extraction and ore processing commenced.
The ore is composed of lead and zinc sulphides (galena and blende) accompanied by silver. Drilling and blasting were the principal extraction methods underground, using pneumatic percussion drills. The broken ore was loaded by mechanical shovels onto trams and hauled by horizontal gallery to the extraction shafts. At the laverie, ore processing used a flotation system in which finely ground ore suspended in water was treated with organic reagents causing the galena grains to attach to air bubbles and rise to the surface as a mineralised froth, which was collected and dewatered to produce a concentrate containing approximately 75 per cent lead metal. The concentrate was dispatched to the lead smelter at Noyelles-Godault. Tailings were pumped to a settling pond behind a dam at the Colombier lieu-dit south of the Mas du Bosc.
From 1964 extraction was conducted by the initial method of chamber-and-pillar working. From 1973 a selective method was adopted, combining backfill and timbering in high-grade fractures and faults with galleries opening to surface. Production in 1965 already reached 275,000 tonnes of raw ore. After 1973, and particularly following the first oil crisis, the mine enjoyed its most profitable years. At peak operation the workforce reached approximately 153 people. Total output from the start of extraction in 1964 to final closure amounted to 9.6 million tonnes of ore, yielding 356,203 tonnes of lead, 68,569 tonnes of zinc, and 750 tonnes of silver, making the Largentière mine the largest lead mine in France during its operational period.
Economic deterioration and resource exhaustion led to a decision to close the mine. The Compagnie ended extraction definitively in 1983. After closure, approximately 800 kilometres of underground workings were flooded; entrances were sealed, with eighty per cent of the workings inundated. One gallery entrance on the old Chassiers road remains visible.
The principal surviving surface structure is the imposing 47-metre concrete tower of the puits de Montredon, which stands surrounded by the buildings of the ore crushing plant, laverie, and workshops. These industrial structures, characteristic of their period, remain largely intact but show deterioration from minimal maintenance over five decades since closure. Part of the collective workers' housing built by Peñarroya also survives. The tailings dam at the Colombier is still visible, and the former decantation lake covering approximately 24 hectares has been overlaid by a photovoltaic installation. Environmental studies conducted between 2018 and 2021 by Géodéris identified the former Largentière mine concession as one of the highest-risk former mining sites in the Ardèche department, recommending monitoring, soil covering, water treatment, and other measures.
