Moinho deposit

Aljustrel Mine, Aljustrel e Rio de Moinhos, Aljustrel, Beja, Portugal

Moinho, Mina de Aljustrel, Aljustrel, Distrito de Beja, Portugal

Key Information

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The Moinho deposit is in Aljustrel, Beja, Portugal, part of the Iberian Pyrite Belt, known for rich minerals.
It produces uncommon minerals like ferricopiapite and fibroferrite, alongside common ones like pyrite and chalcopyrite.
Research suggests it formed from volcanic activity 359–353 million years ago, hosted by felsic volcanic rocks.
Mining started in Roman times, with modern activity from 1850, now focusing on zinc and lead.
Aljustrel’s culture is tied to mining, with historical sites and a blue pigment, Azul de Aljustrel, from local minerals.
The area has a Mediterranean climate, hot and dry in summer, mild and wet in winter, with average temperature around 16.8°C.

Geographic Location

The Moinho deposit is located in Aljustrel, a town in the Beja district of southwestern Portugal, part of the Iberian Peninsula. It’s in the Alentejo region, known for its vast countryside, and is about 34 kilometers southwest of Beja. The deposit is part of the Aljustrel Mine complex, which includes nearby orebodies like Feitais and Estação, and is close to the Neves-Corvo mine, about 40 kilometers southwest.

Minerals Produced

The Moinho deposit is a treasure for mineral enthusiasts, producing a variety of minerals. Common ones include pyrite (FeS2), chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), and baryte (BaSO4). Uncommon minerals like ferricopiapite, fibroferrite, butlerite, and römerite are also found, often as secondary minerals formed from sulfide oxidation, adding vibrant colors and unique formations to collections.

Geological Structure

Research suggests the Moinho deposit is a Volcanogenic Massive Sulfide (VHMS) deposit, formed from volcanic activity around 359–353 million years ago during the Lower Carboniferous period. It is hosted by felsic volcanic rocks of the Mine Volcanic Unit, part of a complex structure with folds and faults, including the Messejana fault, in the Iberian Pyrite Belt.

Mining History

Mining at Moinho and the Aljustrel Mine dates back to Roman times, known as Vipasca, with advanced techniques used for pyrite. Modern mining began in 1848, with extensive exploitation from 1850 to 1993, restarting in 2008. Initially focused on copper, it now emphasizes zinc and lead, reflecting the region’s economic and historical significance.

Local Culture and Characteristics

Aljustrel’s culture is deeply rooted in mining, evident in landmarks like the Aljustrel Mining Heritage Route, featuring the Vipasca Well and São João pruning site. The town is also known for Azul de Aljustrel, a blue pigment from local minerals, historically sold to painters. The Ethnographic Museum showcases local life, highlighting agriculture and crafts alongside mining heritage.

Climate and Ecology

The area has a Mediterranean climate, with hot, dry summers and mild, wet winters. The average annual temperature is around 16.8°C (62.3°F), with July being the driest month (2 mm precipitation) and October/March the wettest (around 50 mm). The ecology features grain fields, olive groves, and cork oak trees, typical of the Mediterranean landscape.