Age of the Longstone Builders | The Bronze Age 2300-800 BCE
Metallurgy in the Bronze Age
The remnants of tin streaming, Porthmeor
One catalyst of change was the use of bronze, used in blades, axes, needles, mirrors, razors, ornaments and other paraphernalia, making them more durable, sharp, polished and useful than ever before. Increased productivity brought greater wellbeing, enhanced crop yields, better crafts and woodwork and a host of other benefits. Penwithians’ lives were changing.
It started with copper. West Penwith had only small deposits, though North Wales and the west of Ireland had better ones. In the earliest days in Penwith, gold and copper could be picked up from the ground, found in streams or shallow-buried in the area between Sennen and Botallack and in places elsewhere. Tin was Penwith’s big asset and, as bronze-working grew, Penwith and other parts of Cornwall and Dartmoor did well. Deep mining was rare because streaming was easier, although they would dig around if tin was present below the surface, which they could tell by looking for indicator plants and other signs (or the absence of them), and by intuition and dowsing.
Streaming was a common technique. This involved channelling and re-routing streams to loosen and erode their banks, exposing metal-bearing stones that could be caught in the stream, shattered, sorted and smelted. There are quite a few streams in Penwith where signs of streaming remain – though much of it is from relatively recent centuries, in some cases started in earlier times. Steep-banked streams cut extra deep, with discernible valley levels, are visible in Kenidjack valley, Cot Valley, at Nanquidno, Bosigran and Porthmeor. Metals were initially exported as ore ingots to Ireland, Wales and elsewhere. Only later, around 1800 BCE, did Penwithians develop a forging and metalcraft industry of their own. After 2000 BCE Penwithians also developed copper and gold streaming.
Early hard-rock mining was done by setting fires close to metal-bearing rocks to heat them, and then shattering them with water poured onto the hot rock. Sometimes metal would flow out during the burning but, after shattering with water, pieces could be prised out with wooden and bone tools, hammered with stone, then sorted to pick out metallic bits. Copper starts to melt at 1083˚C and bronze at 830-1,000˚. Moulds often contained quartz, which melts at 1,500-1,750˚. To make copper useful for pouring and moulding in stone, clay or bronze moulds, often quartz-lined or made of quartz-rich rock, had to be heated to around 1,300˚C in pottery crucibles and poured quickly and competently into the moulds – small errors could render a copper or bronze piece useless. Metalsmiths were highly trained specialists, some of them probably peripatetic, possessing some social and religious status.
Bronze is comprised of 88-90% copper plus 10-12% tin. Tin was a thus a high-value commodity and, because of the proportions used, tin was taken to copper, and not the other way round. Arsenic, cobalt and other metals serve as key hardening ingredients in bronze, and deposits found around Botallack and St Just were rich in them. These marker ingredients made for sharper, more durable blades for tools and weapons, and they have helped archaeologists determine that Cornwall’s export market stretched as far as the Rhineland, the Baltic and the Mediterranean.
The richest part of western Eurasia was the East Mediterranean. It had two main sources of quality tin – Cornwall and Afghanistan. Supplies from both met at the ancient port of Ugarit in today’s Lebanon, at the east end of the Med and the west end of the Silk Road. Traders did not travel all the way from Cornwall to Lebanon: the tin was passed from trader to trader, first to Brittany, down the French coast, up the Loire or Garonne, down the Rhone and across the Med to Sicily, Crete, Egypt, Lebanon and Cyprus, the richest copper source at the time.
Cornish tin also travelled down the Atlantic coast to the Carthaginian port of Tartessos in the eastern Algarve, then through the Pillars of Hercules into the Mediterranean. Here lies the tradition of Phoenicians visiting Cornwall, against which there is much archaeological scepticism, though this might be excessive, overriding a fair assessment of historical probability. A few Phoenician ships might well have come to Cornwall, one possible explorer being Himilco in the 500s BCE. Individual traders or agents would come up on Breton boats to visit trading contacts and the mysterious Tin Islands.
Tin trading likely took place at St Michael’s Mount, Porth Curno, Porth Ledden, Porth Nanven, Lelant, Carnsew and St Ives.
Though mariners chose their summer sailing days carefully, with noses to the wind and an eye on the currents and weather, Penwithian culture would have been greatly influenced by its summer visitors. The metals trade depended on intrepid sailors. They built seagoing boats of wood with leather sails, to withstand journeys to mainland Europe and up the Celtic and Irish Seas. Tin ingots, heavy but not large, were quite transportable and high-value.