Giunchi stream prospect (Montenero), Terzorio, Imperia Province, Liguria, Italyi

Regional Level Types
Giunchi stream prospect (Montenero)	Prospect
Terzorio	Commune
Imperia Province	Province
Liguria	Administrative Region
Italy	Country

A small occurrence of argentiferous galena is located in the Rio Giunchi valley. The site was abandoned around 1857 due to the limited amount of exploitable material.

The mineralization occurs within the rocks of the Sanremo Flysch (San Michele Member), along a fault system that facilitated the circulation of hydrothermal fluids.

The first mineral to crystallize was galena, found as centimetric crystals mostly included within quartz, together with baryte, which occurs as large milky-white tabular crystals, also mostly included. Quartz subsequently crystallized, coating numerous rock cavities and forming characteristic aggregates of short, stubby crystals, mostly milky but sometimes bluish due to the underlying argillitic matrix. Finally, calcite crystallized, occasionally covering the quartz crystals. Beautiful smithsonite crystals can be found in areas where galena has undergone dissolution, greenockite is rare and it is present as earthy yellow coatings also in ex-galena sites and along fractures of undissolved galena crystals.

Both mines were developed along fault zones; however, the western mine is no longer accessible due to a collapse that blocks its entrance. Mineral collectors are advised to exercise caution, as the only remaining accessible mine is structurally unstable. Mineralized boulders and waste material from the two mines can still be found along the stream bed.

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References