Ruina Montium is a mining method used by the Romans, during the first centuries A.C. in the Spanish alluvial gold deposit. The method consisted in using the strength of torrents of water to "wash" huge portions of alluvial terrain and finally make the bench collapse, for the process to be applied to a new bench.
Pliny The Elder described this amazing mining method we described in a previous article. To our knowledge Pliny is the only source available on the subject which raises at least two questions.
A Contemporaneous Method With Pliny?
Pliny the Elder described this very impressive extraction method, applied in large-scale extraction sites. The Pliny testimonial we have about Spanish sites, especially related to the Las Medulas mine is most likely to be an eyes-witness description as he was procurator of Hispania Tarraconensis on behalf of his friend, the Emperor Vespasian. Archaeological evidence and specialist analysis show that the Las Medulas mine had been operated for at least 250 years (Bird, D.G., The Roman gold mines of North-West Spain, 1972)
Strabo’s (64 B.C- 21 A.C.) account about Spanish gold-washeries did not explicitly mention the Ruina Montium technique:
"Turdetania [region encompassing the Guadalquivir valley from the Algarve to Sierra Morena occupying most of present Andalusia], however, and the surrounding districts surpass so entirely in this respect, that however you may wish, words cannot convey their excellence. Gold, silver, copper, and iron, equal in amount and of similar quality, not having been hitherto discovered in any other part of the world. Gold is not only dug from the mines, but likewise collected; sand containing gold being washed down by the rivers and torrents. It is frequently met with in arid districts, but here the gold is not visible to the sight, whereas in those which are overflowed the grains of gold are seen glittering. On this account they cause water to flow over the arid places in order to make the grains shine; they also dig pits, and make use of other contrivances for washing the sand, and separating the gold from it; so that at the present day more gold is procured by washing than by digging it from the mines." (Strabo, Geography (3.2.8), Translation by H.C. Hamilton, Esq., W. Falconer, M.A., Ed.)
Pliny was in Spain around 70 A.C, more than 50 years after Strabo wrote his Geography so maybe Ruina Montium was not yet practiced at that time.
A Widely Used Technique?
The description of the Ruina Montium process we find in Pliny’s Natural History, has undoubtedly a high documentary value. It gives nevertheless no evidence to prove that thee technique was used elsewhere in the Empire.
In his Geography, Strabo depicted a system based on "trenches cut for drawing water" in Northern Italy :
"The country of the Salassi [in Northern Italy] contains gold mines, (…). The river Doria Baltea afforded them great facility in obtaining the metal by [supplying them with water] for washing the gold, and they have emptied the main bed by the numerous trenches cut for drawing the water to different places. This operation, though advantageous in gold hunting, was injurious to the agriculturists below, as it deprived them of the irrigation of a river, which, by the height of its position, was capable of watering their plains." Strabo, Geography (4.6.7), Translation by H.C. Hamilton, Esq., W. Falconer, M.A., Ed.
The Salassi’s system seems more likely to be a large scale gold-washery as no mention is made of the most impressive part of the technique: the collapse of mountains.