Serra da Mina Mine

The Serra da Mina Mine is situated in Cercal do Alentejo, a small town in the Santiago do Cacém municipality, Setúbal District, Portugal. This location is part of the Alentejo Litoral, a sub-region known for its rural landscapes and proximity to the Atlantic coast, less than 15 km from several beaches. The coordinates are approximately 37° 47' 25'' North, 8° 42' 28'' West, placing it in a region rich with natural beauty and historical significance. Nearby settlements include Cercal (3.2 km away, population 3,772), São Luis (9.1 km, population 1,006), and Vila Nova de Milfontes (9.9 km, population 4,393), offering a blend of coastal and inland exploration opportunities. The area is also part of the Southwest Alentejo and Vicentina Coast Natural Park, enhancing its appeal for nature enthusiasts.

The mine is notable for producing 21 valid minerals, with a focus on iron and manganese. Key minerals include baryte (BaSO4), braunite (Mn2+Mn3+6(SiO4)O8), chlorargyrite (AgCl), cryptomelane (K(Mn4+7Mn3+)O16), goethite (Fe3+O(OH)), hematite (Fe2O3), pyrolusite (Mn4+O2), and quartz (SiO2), among others. Manganese oxides and hydroxides, such as pyrolusite and cryptomelane, are particularly striking, often forming dendritic patterns and botryoidal shapes that captivate collectors. These unique formations make the mine a treasure trove for mineral enthusiasts seeking both scientific and aesthetic value.

The Serra da Mina Mine is located within the Iberian Pyrite Belt, a globally significant metallogenic province known for its Paleozoic volcanic and sedimentary rocks rich in massive sulfide deposits. While specific geological maps for the exact location are not readily available online, the region’s geology is characterized by complex formations including oxides, hydroxides, sulfates, phosphates, and silicates. This suggests a history of volcanic activity and mineralization, with the mine’s focus on iron and manganese ores reflecting the belt’s rich mineral potential. The presence of these minerals indicates a dynamic geological history, appealing to those studying the region’s tectonic and mineralization processes.

Active until 2000, the Serra da Mina Mine was primarily involved in extracting iron and manganese, contributing to the industrial heritage of the Alentejo region. Since its closure, the mine’s galleries have been sealed, marking the end of operations. This history is part of a broader narrative of mining in Portugal, with the region having been exploited for various minerals since ancient times. The mine’s inactivity since 2000 reflects changes in the global mining industry, but its legacy continues to influence local geology and mineral collecting communities.

Cercal do Alentejo, with a population of about 3,800, is deeply rooted in agriculture and mining, shaping its cultural identity. The town’s name, derived from the Latin "circulus" (circle), may reflect its layout or surrounding hills. Cultural landmarks include the Igreja Paroquial do Cercal (Church of Nossa Senhora da Conceição) and the Ermida de Nossa Senhora da Bica, reflecting its historical and religious heritage. Traditional festivals celebrate the region’s natural resources and history, fostering a strong sense of community. The official website for the town, Cercal do Alentejo, provides further insights into local events and heritage.

The climate in Cercal do Alentejo is temperate, with mild winters and warm summers, typical of the Mediterranean region. This climate supports diverse ecosystems, including coastal dunes and inland cork oak forests (montados), iconic to the Alentejo landscape. The area is part of the Southwest Alentejo and Vicentina Coast Natural Park, known for its biodiversity, offering opportunities for hiking, birdwatching, and exploring untouched natural beauty. The park’s protected status highlights its ecological importance, contrasting with the mine’s industrial past and providing a rich backdrop for ecological studies.