Roman Copper Mining
It is known that copper recovery was well known to prehistoric man and to the ancient civilisations of the middle east.
Some of these ancient civilisations especially those of the Etruscans around the mountainous regions of Italy had by 800 BC also discovered Iron. In their sea faring trade, they eventually came up against the Romans.
Rome was exploring all around the Mediterranean for mineral wealth to support its growing empire. It has sacked the last Etruscan city by 400 BC and knew about Copper and Iron. By this time most weapons were being made of Iron and Copper and Bronze was being used for decoration.
After destroying the Phoenician city of Carthage the Romans came into possession of the Spanish Copper and Iron mines at Rio Tinto. The name Rio Tinto means coloured river. The water runoff from the mines coloured the rivers in the area. In much the same way as the rivers which run from Parys Mountain are coloured and are known in Welsh as Afon Goch which means red river.
The mine at Rio Tinto was still worked by the old method of fire setting. In addition, quicklime was forced into cracks in the rock and then wetted, the expansion causing the rocks to crack. What was once a mountain in the time of the Romans is still worked today. It is now a crater over 800 feet deep. In the walls one can see remnants of Roman tunnels and shafts. Water wheels with bronze axles were used to lift water. The wheels were driven by slaves on a treadmill. All his points to the Romans using there engineering skills to improve the efficiency of ore removal.
The surface ore at Rio Tinto was the green and blue oxide materials. However, the lower levels were the sulphide ores such as chalcopyrite. These ores were much harder and more difficult to smelt.
This is the world’s most important copper ore with about 80% of the world’s copper derived from this ore.
The Romans found a way of recovering copper from the chalcopyrite which was based on leaching rather than smelting. They collected the water that seeped through the mines. The copper saturated water was a deep blue and consisted of mainly copper sulphates. These made the water very acidic and the water was called Chalcanthus. This material was allowed to dry to make a solid copper sulphate light blue material called chalcanthite.
The Roman Empire had to expand to mine outside their boundaries to maintain their wealth. It is known that one of the reasons that Julius Caesar invaded Britain was to take control of the Tin deposits in Cornwall.
The evidence for Roman copper mining at Parys mountain is based on the existence of two bun shaped copper cakes, now in the British Museum. They were found near the Trysglwyn farm on the mountain. The cakes weighed between 25 and 30 pounds and one was stamped. IVFS.
This copper cake found at Mynydd Parys is 12.5 inches in diameter and weighs 32 pounds.
Up to 18 such cakes have been found on Anglesey some weighting up to 42lb. Smaller segments have also been found. One was found in 1945 near Tregele. The whole piece would have been around 12 inches in diameter and weighed about 40 pounds.
Another piece was found near LLanbedr Goch in 1971. From the piece it could be seen that it had been collected in a round bottom bowl after the smelting process. The fragment also showed signs of it being broken by hammer and chisel just after it was cast.
Most of the copper ingots found in the county have been un broken. At least 8 of the 18 bear Roman stamps. These include three found at Rhosgoch and two found on Parys mountain.
It is thought that the ingots were being manufactured at Parys mountain for export to other areas of Britain. There have been some attempts to correlate the positions of the ingot finds with some of the early Romano British hut settlements on the island. However, other than the Ty Mawr site at Holyhead, little evidence of copper work has been found at the hut sites. Evidence of Iron working has been found. It is hence thought that the natives of the island took little part in the working of the copper once it was extracted from the mine.
It is thought that the Roman fortlet at Caer Gybi (Holyhead) was built in the 4th century partially to protect the mineral reserves of parys mountain.
No copper ingots have been found at the other copper mine of the Roman period which was situated on the Great Orme.
The mining of copper at Parys mountain stopped when the Romans left Britain. By this time all the easily won ore at Rio Tinto was also at an end. It was left for others in the middle ages to discover methods of efficiently removing copper from the sulphide ores.