Sierra Minera de Cartagena-La Unión is a mountainous formation that extends along 26 km of coastline from the city of Cartagena in the west to Cape Palos in the east, through the municipality of La Unión, in the Region of Murcia in Spain. Its maximum elevation is located on the Sancti Spíritus hill near Portmán, at 431 m altitude.
This mountain range was intensely exploited for its silver and lead mines and other metallic minerals in ancient times. The control over these mining resources was one of the main causes of the establishment of the Carthaginians in southern Spain and the subsequent Roman occupation. The prosperity generated by mining made the city of Carthago Nova, now Cartagena, one of the most flourishing in Roman Hispania, until the end of the 1st century, due to the depletion of the best deposits, along with the scarce Roman technology, it was abandoned.
The mines were not exploited again until the 19th century, when new industrial technologies made mineral production in the Sierra de Cartagena profitable again, and there was a new mining and related industries boom. After the Spanish Civil War, extensive open-pit mining was introduced, which caused serious environmental problems until mining activities ceased definitively in 1990.
As a consequence of this long historical process of industrial exploitation, the landscape of the Sierra de Cartagena-La Unión is marked and transformed by centuries of intense human activity and treasures valuable cultural, archaeological and industrial testimonies of its mining past. For all these reasons, it has been declared a good of cultural interest (in Spanish: Bien de Interés Cultural) with the category of historic site.
Geological origin
Orogeny
The Sierra Minera is part of the last eastern foothills of the Baetic mountain ranges, which arose in the Cenozoic during the so-called Alpine orogeny, due to the collision of the Mesomediterranean microplate with the Iberian plate. Geologically, the Sierra Minera is composed of two superimposed tectonic units:
A very old one belonging to the snow-phyllabid complex, originated during the Paleozoic and composed of metamorphic materials, mainly mica-schists. It appears in the form of very dark slate-like rocks in the easternmost part of the highlands, in the surroundings of Calblanque, Cala Reona and Cabo de Palos. Another more modern section, formed during the Triassic and corresponding to the alpujárride complex that is superimposed in the form of a mantle to the previous one. It is composed of metamorphic and sedimentary rocks, mainly limestone. It arises in the center of the highlands, in the Monte de las Cenizas, and extends westward through the area of Portmán, La Unión, the Sierra de la Fausilla and reaches the port of Cartagena.
Volcanic origin of the mineral deposits During the Late Miocene, the Campo de Cartagena suffered one of the most recent episodes of volcanism in the Iberian Peninsula. About seven million years ago, numerous volcanic eruptions began to occur throughout the area, the remains of which are: the islands of the Mar Menor, Isla Grosa, El Carmolí or Cabezo Beaza. The last eruptions took place only one million years ago, in the Cabezo Negro de Tallante.
Associated with this volcanic activity, powerful hydrothermal processes were generated, where water from the interior of the Earth, with presence of dissolved minerals, subjected to strong pressures and high temperatures, precipitated these minerals in the faults and cavities of the mountain range, and gave rise to rich veins of metallic minerals.
Mineral deposits and mineralogy The mineralogy of the Sierra de Cartagena-La Unión is quite complex, and the exploitation of the deposits has had different approaches depending on the time. In Roman and pre-Roman times, the main mineral was silver, contained in the argentiferous galena and gossan. Along with it, enormous quantities of lead were extracted, but lead-rich slag was also abandoned. Between the end of Roman exploitation and the 19th century, mining was sporadic, mainly to obtain galena for pottery (alcohol for potters) or even amethysts, of reasonable quality in the context of European deposits, before the exploitation of South American deposits. In the 19th century, the exploitation of lead was resumed from the old slags, then from the secondary minerals (anglesite and cerussite) despised by the Romans, and finally from galena, obtaining also silver. Zinc was obtained since the mid 19th century from oxidized minerals, the so-called calamines (smithsonite and hemimorphite) and since the beginning of the 20th century also from sphalerite. Iron ores (limonite and siderite) were also extracted in many mines, especially when they contained manganese (mixtures of goethite and pyrolusite). At certain times tin ore (cassiterite) was also extracted in some specific mines, as well as copper ores (mainly in prehistoric times) and baryte. From the mineralogical point of view, the Sierra minera de Cartagena-La Unión has produced remarkable specimens of most of the exploited species, and other minerals without industrial value, but of scientific interest, such as greenalite, vivianite or ludlamite.
Mines of Cartagena in antiquity
Archaeological evidence The earliest archaeological evidence of mining in the southeast comes from the numerous Phoenician shipwrecks that attest to commercial exchanges of mineral products with the East from the 7th century BC. Proof of this commercial traffic is, for example, the cargo of a sunken Phoenician ship found on the island of Grosa, near Cape Palos, consisting of lead and tin ingots together with Punic artefacts and elephant tusks with Phoenician inscriptions. This cargo is preserved in the National Museum of Subaquatic Archaeology in Cartagena.
An exceptional site also on display at the National Museum of Subaquatic Archaeology is that of the Phoenician ships of Mazarrón, whose lead cargo, although not exactly from the mining area of Cartagena, demonstrates the existence of mining operations in the region since the 7th century BC.
The first archaeological evidence of a settlement dedicated to mining in the highlands dates back to the Iberian period, since in the town of Los Nietos, next to the Mar Menor, a settlement was discovered in the 1960s that in the 4th century BC served as a commercial base for the area, where products derived from mining were exchanged for goods from Greece, Campania and the eastern Mediterranean.
Carthaginian dominion over the mines of Cartagena
According to some historians, such as the well-known archaeologist Adolf Schulten, the establishment of the Carthaginians in the southeast of the Iberian Peninsula and the foundation of the city of Qart Hadasht, today's Cartagena, in 227 BC by Hasdrubal had as its main objective the control of the wealth generated by the silver mines of Cartagena.With the silver from the mines of Cartagena they paid their mercenaries, and, when by the capture of Cartagena in 209 BC Carthago lost these treasures, Hannibal was no longer able to resist the Romans, so that the capture of Cartagena also decided Hannibal's war.
Adolf Schulten, Fontes Hispaniae Antiquae.With this silver would most probably have been produced the minting in the city of a well-known series of Carthaginian coins with the effigies of the Barca family found in Mazarrón and in other points of the Levant in the 19th century.
Mines of Carthago Nova in classical sources Mentions of the mineral abundance of all Hispania are constant in the descriptions of the Peninsula made by classical historians in antiquity. The extraordinary richness of the silver mines of Carthago Nova immediately attracted the attention of Greek and Roman geographers. The first written references that refer specifically to the mines of Carthago Nova come from the historian Polybius of Megalopolis, who visited the area in 147 BC. After describing the city in detail, the writer relates the existence of a hill with a temple dedicated to Aletes, discoverer of the silver mines.The other elevations of the terrain, simply a few hills, surround the northern part of the city. Of these three, the one facing east is called Hephaestus', the next one, that of Aletes, a personage who, it seems, obtained divine honors for having discovered the silver mines.
Polybius, Histories 10, 11.1.A century later, the geographer Strabo, paraphrasing Polybius, describes the silver mines of Carthago Nova at slightly greater length.
Polybius, in mentioning the silver mines of Carthago Nova, says that they are very large, that they are about twenty stadia ('about four km') from the city, that they occupy an area of four hundred stadia ('about seventy-five km'), that forty thousand workers work in them and that in his time they brought the Roman people 25,000 drachmas a day. And I omit all that he relates of the working process, because it is too long to describe; but not that concerning the argentiferous gangue carried by a stream, which, he says, is crushed and separated from the water by means of sieves; the sediments are crushed again and again filtered and, thus separated from the water, crushed once more. Then, this fifth sediment is melted and, separated from the lead, pure silver remains. At present the silver mines are still active; but here, as elsewhere, they have ceased to be public.
Strabo, Geographica, Book III.Traditionally it has been considered that the following text of Diodorus of Sicily, a contemporary of Strabo, referred to the silver mines of Cartagena, although without mentioning them explicitly.This use (of silver) being unknown among the natives of the country, the Phoenicians used it for their commercial gains, and when they realized this they acquired the silver in exchange for small goods. Thus the Phoenicians who carried it as far as Greece and Asia, and all other peoples, acquired great wealth. To such an extent did the merchants strive in their eagerness for profit that when there was plenty of silver left over because the ships were full of cargo, they substituted silver for the lead in the anchors.
Diodorus of Sicily (Bibliotheca historica V, 35, 4–5).
Exploitation of the mines of Carthago Nova during the Roman domination
In 209 BC, in the context of the Second Punic War, Scipio Africanus, motivated by the interest of taking control of the silver production of Cartagena, conquered the city of Qart Hadasht for the Roman Republic, renaming it Carthago Nova and granting it the status of municipium."The rapid march of Scipio to conquer Cartagena is very possibly due, not to the necessity of depriving the Carthaginians of the best port they had on the Levantine coast in their relations with Africa and Italy, but to the need to control the rich silver mines of the surroundings that financed the Second Punic War. Once these were lost, Hannibal remained practically on the defensive in Italy".
BLÁZQUEZ, José María. «Explotaciones mineras en Hispania durante la República y el Alto Imperio Romano.» Anuario de Historia Económica y Social en España 2, (1969).
At first, the workings of the mines were under the direct control of the State. Rome exploited the mines of Cartagena using both the underground mining and "open-pits". From this period comes the famous Cabezo Rajao mine, where a superficial vein of argentiferous galena was emptied, leaving a large crack in the mountain, the origin of its current etymology.