A briefing of Aljustrel mines

Aljustrel Mine may also refer to any of the several metal mines around Aljustrel amongst which the São João copper mine.



The Ossa-Morena Zone and this unit are joined by the Ferreira-Ficalho thrust (partially over the Beja-Acebuches complex), which runs approximately E-W to the east and NW-SE to the west. The South Portuguese Zone is characterised by the existence of a volcanic sedimentary complex from the Late Devonian-Early Carboniferous period, overlain by a Culm flysch sequence; underlying this complex is the so-called "Phyllite-Quartzite Group". The oldest formations in this zone date from the Early Devonian period and belong to the "Pulo de Lobo" Formation, which includes phyllites, quartzites and rare acid and basic volcanic rocks. The acid volcanic rocks in the volcanic sedimentary complex constitutes the metallotect of the massive polymetallic sulphides that are characteristic of the Iberian Pyrite Belt, the most important metallogenetic province in Portugal in which the Lousal, Aljustrel, Neves Corvo and São Domingos mines are located.


The metal exploitation mining and metallurgy in Aljustrel began at the end of the 3rd millennium BC, during the Copper Age, having been collected materials that prove it in the hill of N. Sra. do Castelo, where stood the village of that period. This place is equidistant from Algares and S. João do Deserto gossans, places where the mining activities would take place.

The occupation of the Bronze Age was on the Mangancha hill closer to the veins of S. João do Deserto. With the investigation still ongoing this site, we can not go much further recitals on mining in this period.






At the end of the 1st century BC began the Roman occupation of Mangancha hill and it seems that there was installed a garrison that begun the mining and the construction of a new settlement to be known as Vipasca located nearest Algares with easy access in place now known as Valdoca or Oca Valley. This mining exploitation lasted until the 4th century AC, with fluctuations in production coinciding with the crisis of the Empire, it was then abandoned, leaving behind its industrial character that had until then taken place.






















We only get to find another reference to the existence of a mine in the Foral of 1252, when the Order of Santiago da Espada reserves to itself the income of the mine, perhaps a sign that the mine continued to produce. Later, in the beginning of the 16th century, in the Ayres do Quintal mining regulation's list of existing mines of the country, comes as mentioned the Aljustrel mine. In mid-century, a D. João III's document, refers to the existence of a royal official in Aljustrel that thinned and sold to painters, a pigment known as Aljustrel's Blue.


New chronological gap and, in 1848, is awarded the first grant of mining in Aljustrel to a Spanish citizen, Sebastian Gargamala that conducted few studies thus losing the grant. The same is then assigned to the Lusitanian Mining Company which also only labored it for two years, so the award is then transferred to a Portuguese firm, the Mining Company Transtagana, which starts a large-scale operation for fifteen years, with the introduction of the rail transport and ore processing.


Due to a downturn in the international market, the company ultimately goes broke and the award goes to the bank Fonseca, Santos & Vianna. This bank will be associated to a Belgian company and create the Société Anonyme Belge des Mines d'Aljustrel, which will explore the mine until 1975, although throughout its existence it was associated with new partners and other assumed names.

In 1975 the company was nationalized by renaming itself to Pirites Alentejanas, a name that remained until 2009 although its owner has changed several times. It currently belongs to a Portuguese group taking the name Almina - Minas do Alentejo.

Nowadays, the mining concession is located around the mining village of Aljustrel. The mining area is 4.7 km² wide and includes the deposits of São João, Moinho, Feitais and Estação.





References:
- Leistel, J. M.; Marcoux, E.; Thiéblemont, D.; Quesada, C.; Sánchez, A.; Almodóvar, G. R.; Pascual, E.; Sáez, R. (1997). "The volcanic-hosted massive sulphide deposits of the Iberian Pyrite Belt"
- Schermerhorn, L. J. G.; Stanton, W. I. (2009). "Folded overthrusts at Aljustrel (South Portugal)". Geological Magazine 106
- Barriga, F. J. A. S.; Fyfe, W. S. (1988). "Giant pyritic base-metal deposits: The example of Feitais (Aljustrel, Portugal)"
- Municipal authorities of Aljustrel, "History of mining" (in Portuguese)
- LNEG - Mineral Potential of Portugal (1998)

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Some mineral specimens collected in these mines