Toss a coin to...your emperor

Mining in ancient times was definitely not something people were dreaming to do, but the growing empire needed coins to keep it stable, pay army, build and fill treasuries. Ores were in permanent demand so Rome had to find solutions. As a geologist I am pretty fascinated about ancient mining and quarries, mostly because they had very little technology. Nowadays we can drill kilometers deep into rocks, get seismic profiles, create 3D models, calculate resources and reserves before the actual exploiting process, we know in detail what to expect and how pure the ore is. But in ancient times they knew very little and they were counting on direct physical observations only, creativity and most probable the fear of death... Back then, geology was not the complex science that we have today and parts of it was done separately as mining, quarrying, engineering (roads, buildings, aqueducts, etc.), metallurgy, etc. These people were the engine, minds and the very base of societies, using what nature was having in the basket.

In order to produce coins, romans needed ores as raw material and the italic peninsula does not exceed at it. Quite the opposite I would say, since it has only some zinc (Zn), iron (Fe) and a bit of cooper (Cu). They could be used for lousy coins but roman rulers had high standards and preferred silver and gold. When you don't have something, you have several options: you buy it (not on Rome's list), you get vassal territories and force them to pay taxes, or you get it directly. Last 2 are more exciting, right? Romans thought the same.

Silver coin portraying Augustus and Agrippa sitting back to back. Agrippa is wearing his rostral crown and the head of Augustus is wreathed. On the right side is a crocodile chained to a palm tree with a palm leaf on either side of the base. Minted in Nemausus-Gaul (Nîmes today, on the southern coast of France);(www.romanemperors.com).

Ancient roman mines are documented in UK (ex Britannia), Spain and Portugal (Hispania), Greece (Achaia), Romania (Dacia), Balkans (Thrakia), Austria (Noricum), Gallia, Croatia (Dalmatia), Turkey (Asia Minor), Arabian Peninsula or Cyprus, the romans exploiting rocks associated with past volcanic activity, which means extinct volcanoes or magma intrusions.

Next time you hold a silver or a gold coin in your hand, try to imagine the travel of that specific mineral from the earth's mantle, through the earth's crust and finally to the surface. That's quite an epic journey!

To extract large quantities of material, the romans were counting mainly on non-payed labor. War prisoners, convicted roman citizens or traitors were sent to spend the rest of their lives in Rome's service. Once they got there, for sure their life would not have been long due to extreme working conditions and exhausting. Young, old, women, men, children, no one was spared.

Fortunately, many exploitation places survived until modern days with different degrees of preservation so we have a real grasp of the magnitude of roman mining. By far, the biggest ore exploitation area was the Iberian Peninsula, followed by Britannia. To coin-ore mining were also added Noricum, Dacia and Attica, but also smaller other regions all over the empire.

Hispanic mining was so extensive and intense that Pliny the Elder described the process in his Naturalis Historia and named it ruina montium, which means literally wrecking of mountains. For the ancient world these extensive mining works must have been indeed unbelievable.

" What happens is far beyond the work of giants. The mountains are bored with corridors and galleries made by lamplight with a duration that is used to measure the shifts. For months, the miners cannot see the sunlight and many of them die inside the tunnels. This type of mine has been given the name of ruina montium. The cracks made in the entrails of the stone are so dangerous that it would be easier to find purpurine or pearls at the bottom of the sea than make scars in the rock. How dangerous we have made the Earth! ", Pliny the Elder

Mining is a destructive and irreversible process and the ore that is exploited will not be refiled. An active mining area looks like another planet. Piles of ore, sterile, slag, mining shafts, processing plants, wooden or metal structures, some living cottages and no or very little vegetation. This would have been the landscape more than 2000 years ago in what is now central-south Spain and Portugal, from the Iberian Pyrite Belt geological province. Copper, tin, lead, iron, gold and silver exploited here were the cherry on the Rome's cake. The most famous area was Riotinto, still active until decades ago. The useful minerals exploited here were formed over 370 million years ago, during the Devonian period, when continental land mases collided to form the supercontinent Gondwana, the biggest in Earth's history until that point. Volcanoes that shaped Gondwana were responsible of one of the biggest extinction on our planet and once more got their tribute through the lives of the ancient slaves that died here for the wealth of the roman republic and empire. The hispanic silver denar was used to pay the army and maintain the general political cohesion. The roman "gold rush" was intense for the entire roman expansion, since the 3rd century BC.

Roman water wheel dug in 1919 at South Lode. Photo by Aquilino Delgado.

Another important mining area for the roman coin minting was Britannia. The gold from Dolaucothi (Wales) was exploited through classical mining like Hispania (trenches, galleries), but also by washing the sediments of the river Cothi and older alluvial sediment deposits called placers. The exploitation here started around 80-70 BC and was active for almost 200 years. In 125 BC the romans abandoned the mines, but they were still used for some time by locals.

Our next stop in producing coins is Noricum province in today's Austria. The gold exploited here comes from 2 different geological periods: the first deposits are Permian intrusions from ~260 million years ago, while the second ones are much younger, between 23 and 15 million years old, when the African tectonic plate has its final collision with Europe. This collision shaped the Alps, which were always a pain in the ass for romans. Noricum was also an important source of iron. The iron from here was used mostly for weapons. A high percentage of gladius swords were forged from this very iron.

Another addition on the roman mining map was Dacia, famous for the gold in the Apuseni mountains.

The mines from here were exploited by romans until the beginning of the 2nd c. AD, carved in Neogene deposits (~12 to 7 Ma). The most famous area is Rosia Montana (NW side of the mountains). Most of the galleries are not open to the public because they were flooded over the centuries. A high percentage of the mines in the area are dug beneath the hydrostatic level and require constant water exhausting/pumping, making things quite complicated.

A preserved mining gallery at Catalina Monulesti Mine (Cauuet, B., 2014)

Lavrion is the last place on my list and my favourite I must say. Lavrion or Lavio is located in southern Attica, Greece. The place started to be exploited around 3200 years ago, in the late Neolithic, for copper and led, but while technology advanced, silver and gold came to attention. In modern times zinc and iron were mined here too. Lavrion is a Miocene intrusion of ~11 My, a mountain of useful minerals at the edge of Attica. The ores dug here were separated and melted on spot, or sent further by boat. Lavrion had one of the oldest industrial ports and for hundreds of years was Athens's main revenue source. The Athenian silver tetradrahm was Lavrion's mark in the entire Mediterranen. During roman times, the mines passed through a 'modernisation' process being updated to roman technology level. The mines were active with pauses until modern times and were shut down completely in 1978. Nowadays the place it's a museum, a Unesco heritage site and one of the best preserved ancient mining perimeter in the world.

Left-a water collecting basin; center up- one of the many sterile mounds that dominates the landscape; center down-a modern grave. The person was covered in death with the same material that was digging for. Right-a house taken back by nature. (Last 3 are personal photos.)

Next time you go to Athens, add it to the map. It's also close to Sounio Cape which supports the astonishing Temple of Poseidon! ^^ You're welcome... :)))