Copper Mines
Introduction
For thousands of years before the start of the Irish Bronze Age nearly 4,500 years ago, the people living on this island only had stone, wood, and other items they found in the environment around themselves to use as raw materials. The introduction of metal in the Bronze Age impacted many aspects of people’s lives from the tools they used to the ornaments they wore, but most spectacularly of all, metal transformed their warfare. It also changed people’s perceptions of social standing with the emergence of high status and immensely wealthy individuals and groups.
If you walk in the hills around Caherdaniel, on the south of the Iveragh Peninsula, you might see shallow cave-like openings or under-cuts in the rock faces
Figure 1. Copper mine at Lambs Head
Figure 2. Copper mine at Behaghane also known as St Crohan’s Hermitage
Inside the opening, the surface of the walls may be quite smooth and concave
Figure 3. Interior of copper mine at Behaghane
Patches of a bright turquoise-green colour might be visible on the rock surface. This is staining caused by copper mineralization in the rock
Figure 4. Copper mineralization in Behaghane copper mine
There are many different types of copper mineralization, the most important of which is chalcopyrite. A less obvious clue that copper may be present is the occurrence of Stereocaulon, a rare and protected lichen.
Figure 5. Stereocaulon lichen on rock
Stereocaulon thrives near rocks with copper mineralization at concentrations which are poisonous to other life forms. Most plants, fungi and lichens cannot survive in such metal-rich environments, hence the use of copper sulphate as a herbicide, fungicide, and insecticide. You may also see fresh-looking spreads of rubble close to the opening in the rock face
Figure 6. Spoil heap from a copper mine at Lambs Head
If you see any of the above, you could be at or near an early Bronze Age copper mine. The cave-like openings characteristic of early copper mines were made by breaking the rock face using tools such as hammer stones and antler-picks. The spoil heaps are composed of the waste rock which was discarded once the copper ore had been collected - thousands of years ago.
What artefacts were made with the copper?
At the very beginning of the Bronze Age, copper production was largely limited to flat axeheads, halberds and daggers [1]. Axeheads, the metal versions of their stone counterparts, were made in the greatest quantities and could weigh up to a kilo. Halberds (a scythe-shaped blade which was attached to a wooden handle at a right angle) and daggers were manufactured in smaller quantities. Awls, a pointed tool like a needle which may have been used for leatherwork, were also made. As copper can be melted down and recast into another form, it is probable that many items were recycled. Axe-shaped copper ingots were also made indicating that copper, long before copper coins, was already being used as a form of currency.
As the Bronze Age progressed, an increasing range of metal objects was made, many of these associated with warfare such as spear heads, swords and shields as well as rapiers which were used for stabbing. Bronze was also used for making hunting horns. The Derrynane Horn which is on display in the National Musuem in Dublin is a finely cast horn whose fundamental note, D, is evocative of a stag’s call during the rutting season.
Clues to the origins of the copper used in artefacts
Bronze Age copper artefacts are not composed of 100% pure copper as the metal contains small proportions of impurities such as arsenic, antimony and silver which occur in proportionately distinct quantities across different regions and help indicate where the copper in certain artefacts originated. Smelting and alloying with other metals can also alter the composition of the copper. However, the ratios of lead isotopes in the copper of a particular region remain constant and can be used to link metal artefacts to the sources of the copper used in their manufacture [1]. Studying the composition of copper can help us trace the movement of Irish copper throughout Europe during the Bronze Age. For example, we now believe that artefacts which were found in Brittany in France were made from copper originating at Ross Island in Co. Kerry [2].
Extensive excavations were conducted at the copper mines at Ross Island near Killarney in Co. Kerry, with the earliest evidence for mining of copper dated to 2400 BC (about 4400 years ago) and the use of bronze beginning another 300 years later in 2100 BC [1]. Bronze, a combination of copper and tin, is stronger and more durable than copper alone. During the Bronze Age, goods and ideas were constantly being exchanged throughout Europe. Evidently the metal workers were traders as the tin for the bronze came from Cornwall. Amber and fur were also among the desirable commodities during this time.
How did people first figure out that copper ore can be transformed into metal?
Copper-rich rock and copper metal differ so much in appearance, form and colour that you would wonder how people ever worked out that the reddish-orange metal could be generated from a particular turquoise-green rock? The process of extracting copper from rock which involves heating and melting (and is known as smelting) must have seemed an utterly magical process of transformation! The colour changes are greater still when shiny black tin ore is smelted with copper-rich rock to make bronze. The flames from the furnace change from red and yellow to blue and pink as the ores are transformed into a black liquid which eventually hardens to a bronze, a metal that can shine like gold and serve as a mirror when highly polished.
How was it discovered? Was crushed ore used in pottery for its attractive colour and copper an incidental by-product of firing the clay? Was the turquoise-green copper-rich rock perhaps used in personal adornment and discovered only by chance following a cremation?
In some regions of the world, copper occurs naturally as nuggets in surface deposits with the copper-rich ore deeper in the ground below. In these places, the Copper Age started a long time before ours, as early as 10,000 years ago. Did the turquoise-green patina that coats weathered copper provide the clue that the rock of the same colour and the copper metal are related? If you pour vinegar over an old copper coin, over the course of a few hours, the matt brown of the coin will become encrusted with the turquoise-green colours characteristic of copper-rich rock.
Figure 7 – copper coins with a turquoise-green coating/patina
How did this technology come to be known in Ireland?
To realize that rock could be transformed into metal was a leap of knowledge so great and valuable that it must have been a jealously guarded secret. Distinct groups in different parts of the world appear to have made this discovery independently of one another.
Did the inhabitants of Ireland themselves ascertain that copper ore could be smelted into metal? Before the Bronze Age, the indigenous people had already acquired the technology to create high temperature fires as evidenced by the production of kiln-fired pottery in the country. Any clues that might be provided by folklore and placenames appear to be misleading. Copper mines around the country were often known as ‘Danes’ mines’. But the Danish Vikings are believed to have first come to Ireland only a thousand or so years ago while the early Bronze Age copper mines predate their arrival thousands of years.
Excavations at Ross Island near Killarney in Co. Kerry show that copper mining had already started in Ireland nearly 4,500 years ago, about 2,400 BC . Copper mining appears to have started about 2,600 BC in the Cantabrian mountains in Spain . The possibility that the technology came to Ireland from Spain is supported by the similarity in the mining tools used. Hammer stones from Ross Island in Kerry and those from the Cantabrian mines are very close in form . Although Spain itself had rich copper deposits, access to these resources would surely have been restricted by the groups who controlled them. If prospectors came to Ireland from Spain, had they broken away (or escaped?) from mining communities there? Were the prospectors only seasonal visitors in pursuit of goods from distant places which might have a special value in their home country? Or did they leave their mark here, perhaps bringing other aspects of their culture here, like ‘rock art’? Open-air non-figurative geometric rock carvings which are often referred to as Atlantic rock art are found along the Atlantic fringe especially in the north of Spain and Portugal, Scotland and the north of England as well as Ireland. In this country, the highest concentrations of rock art are found in Kerry. The rock art all along the Atlantic fringe is very similar but it is still open to debate exactly when and how it came into use in each region.
In whatever manner the technology was discovered, information that valuable could not stay a secret for long. Divisions in society would have been growing and the direct link between the mining activities and the fine metal weaponry brandished by the ruling classes would have become self-evident.
At the copper mine complex at Ross Island near Killarney, excavations produced numerous pottery sherds, the vast majority of which are associated with a ‘Beaker’ culture from mainland Europe. Their presence at Ross Island shows that either ‘Beaker Folk’ or Beaker-using groups were involved in the copper mining industry there.
A recently published proposal that the people who introduced copper may have come from the Iberian Peninsula (which is principally divided between Spain and Portugal) concerns recent genetic studies on the ‘strawberry tree’ (Arbutus unedo). This tree, which is widespread in Iberia but rare in Ireland, is not an Irish native tree as previously believed but seemingly introduced to this island from the north of Spain . This tree grows naturally close to the copper mines at Muckross and at Ross Island near Killarney with a few isolated clusters on the south of the Iveragh Peninsula including a smaller number across the bay from copper mines at Lambs Head by the mass path at Derrynane
Figure 8. Flowers and fruit on the Strawberry Tree
Figure 9. Strawberry tree along the mass path at Derrynane
Others grow close to the Kerry Way between Coad and Caherdaniel about 1.5km from Coad copper mine. Its berries, strawberry-like in appearance, can be used to make an alcoholic beverage. Michelline Sheehy-Skeffington and Nick Stott have hypothesised that the tree was brought here by metal prospectors on that account and have created a map which shows both the distribution of the strawberry tree and copper mines which can be viewed here.
The Gold Age
Gold artefacts began to appear in Ireland during the Bronze Age, the gold sourced from deposits in riverbeds rather than mined. Gold appears to have been unknown in Ireland until the Bronze Age. The Beaker culture is best known for its pottery but it is also associated with gold artefacts which include ‘sun-discs’ . These are button-like circular ornaments made of thin sheets of beaten gold with simple raised decoration of which ten have been recorded in Britain and 23 in Ireland. To date, no gold artefacts have been found in association with Bronze Age copper mines in Ireland. However, in Wales, south of the Llŷn Peninsula on the west coast of Wales on Copa Hill, a sun-disc was found within 1km of the Bronze Age copper mine . Within 1km of a great Bronze Age mining complex in Wales, the Great Orme copper mines, the strawberry tree grows naturally on cliffs . Perhaps, like the Kerry examples, this tree was introduced to Wales from Iberia. The same or related groups of people may have been mining at Ross Island and in Wales. Studies have shown striking similarities between the tools used .
Figure 10. The Banc Tynddol sun-disc from Copa Hill in Wales.
Why are early Bronze Age copper mines important?
The discovery of metal changed everything
All history is marked by momentous milestones. The 385 million years old tetrapod tracks at Valentia Island mark a milestone in evolution as various life forms including the 3m-long lizard-like tetrapod transitioned from life in the sea to living on land. During the Stone Age, stone was the multi-power tool of the day. Stone was the key component in everyday devices used for chopping, cutting, hunting and warfare. The increasing use of metal from the beginning of the Bronze Age transformed weaponry, cooking devices, personal adornment and more than anything else, humankind’s relationship to the world around us.
Figure 11 – cobblestone with impact marks at a processing site
Tangible Heritage
Bronze Age copper mines are places we can visit. We can handle a stone shard that was made during copper mining at a time when bears and wolves lived in Ireland and woolly mammoths had yet to go extinct. The sense of connection to the past is enhanced by the fresh appearance of the spoil heaps, caused by the absence of vegetation near the copper-rich rocks. We can see the smooth concave walls in the interior of the mine openings which are evidence of fire-setting, an early Bronze Age technique which causes rapid temperature changes which stress the rock and make it easier to break . The rock face was first heated by fires which were set at its base and then later rapidly cooled by dousing with cold water. The rock was removed using picks made from deer antlers as well as hammer stones that were sometimes attached or ‘hafted’ to a wooden handle as evidenced by tell-tale grooves in on the rock surface. Cobbles gathered at the shore were used to make the hammer stones, occasional examples of which we can still see for ourselves at these sites.
Copper mines are rare
Early Bronze Age copper mines are very rare island-wide and the few that are known are mostly inaccessible being either fenced off or waterlogged. Fortunately, the examples we have in south Kerry on the Iveragh peninsula are not alone accessible, but the effort involved in getting to them is more than repaid as they also happen to be in areas of outstanding natural beauty. The locations of the copper mines in Ireland are indicated on the map below . The mines on Iveragh are shown in this interactive story map, Copper mines on Iveragh. Mines on the Iveragh peninsula include the Bronze Age mine at Staigue which is close to the Iron Age enclosure, Staigue Fort. The copper mines at Behaghane and Coad can be accessed from the Kerry Way between Caherdaniel and Coad.
If you do find a hammer stone or any other artefact at or near a copper mine, please leave it exactly where you found it so that the next person after you can also get the sense that the people mining here some 4,500 years ago have just gone off on a break and are returning any minute now.
