Pestarena gold mine (Pestarena Mines), Macugnaga, Verbano-Cusio-Ossola Province, Piedmont, Italyi

Regional Level Types
Pestarena gold mine (Pestarena Mines)	Mine
Macugnaga	Commune
Verbano-Cusio-Ossola Province	Province
Piedmont	Region
Italy	- not defined -

Pestarena gold mine (Pestarena Mines), Ossola Valley, Verbano-Cusio-Ossola Province, Piedmont, Italy

Pestarena, the most important historical gold mine complex in the Alps, is located in Macugnaga and Ceppo Morelli municipalities.

This mine site interests an area of 4 km2 through about 40 km of tunnels on 15 main exploitation levels. The orebodies are composed of gold-bearing post-metamorphic structures, represented by mineralised cataclasites and veins, often discontinuous and with complex structural geometry. Gold mineralisation is hosted by the Monte Rosa Unit, comprising a sequence of paragneisses and micaschists with minor amphibolites, overlain by an orthogneisses unit. The Pestarena mine is developed within the paragneisses and micaschists, while in the adjacent Lavanchetto property, east of Pestarena and part of the Pestarena mining concession, the gold mineralisation occurs within the overlying orthogneisses. Depending on the host-rock lithology, the ore bodies show strongly different features: they occur along fractures and shear zones crosscutting the foliation at high angle within the hard orthogneiss unit, while are sub-parallel to the foliation within the micaschists and paragneisses (Stella, 1943). Particularly, at the Pestarena mine gold occurs along cataclastic bands and extensional veins mostly oriented WNW-ESE. Veins mineralogy is dominated by quartz, with subordinate carbonates, sericite, chlorite, tourmaline, rutile, apatite, and amphibole. Metallic minerals are typically pyrite and arsenopyrite, with minor pyrrhotite, sphalerite, galena, chalcopyrite, and tetrahedrite. Gold is invariably associated with sulfides, mainly with pyrite and galena.

In the second half of the 19th century the variously owned mines (generically Pestarena mines), which were intensively exploited since the 18th century (Nicolis de Robilant, 1784-85; Amoretti, 1794; De Saussure, 1796; Barelli, 1835), became sections of a larger British enterprise, "The Pestarena United Gold Mining Comany Ltd.". The most known of them are named: Acquavite, Cavone, Morghen, Peschiera, Pozzone-Speranza, Scarpia, Trappola. In 1902 the ownership passed from the British enterprise to the Italian company Pietro Maria Ceretti of Villadossola. In 1938 the mining complex was nationalised and transferred to the state-owned mining company Azienda Minerali Metallici Italiani (AMMI). In 1951 the Italian state granted to AMMI a mining concession, containing the Pestarena and Lavanchetto properties, valid until 2040. The old workings at Pestarena focused on exploiting the easiest (and highest-grade) portions. Gold-bearing ore was also extracted from other veins of the Pestarena mining concession, i.e. the veins Lavanchetto, Fornale, and Caccia, located at higher elevations E-SE of Pestarena. After World War II, however, production costs continued to grow as gold grade declined. Consequently, the mine was abandoned in 1961, leaving approximately 300,000 tons of ore at site with a gold content of at least 7 g/t. In recent times, the company Miniere di Pestarena S.r.l. has taken over the mining concession (which includes also the adjacent Lavanchetto property) and plans to re-evaluate and potentially reopen the mine.

Pestarena mine, in the true sense of the word, includes underground workings between elevation 700 and 1031 m a.s.l. and consists of three main NW-SW-trending mineralised veins, named "Liz", "Quarzo", and "Uno" (De Angelis, 2003). The ore bodies are accessed through two ways: one, the main decline, starts from Pestarena village (Macugnaga municipality) at 1031 m and descends to 700 m, the other, the Morghen haulage level (2300 m long and equipped with mining electrical rail) starts from 870 m and connects the exploitation levels with the ore processing facility at Ceppo Morelli, which now lies abandoned.

Other Regions, Features and Areas containing this locality

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