Lifting Copper and Tin Ingots from the Uluburun Ship Wreck
Yesterday’s blog reminded me to talk about tin, the rare metal required for bronze. In antiquity, bronze was made from 90% copper and 10% tin. Bronze has a considerably higher yield strength than copper – yield strength is the maximum stress that can be applied to a material before it changes shape. For bronze it is typically 250 – 650 MPa whilst it is only 33 MPa for copper. Bronze has also a better tensile strength, the amount of stretching a metal can withstand before being permanently damaged. It is 350 – 635 MPa for bronze and 210 MPa for copper. Bronze is also 10 times harder than copper and melts at 913 Celsius whilst copper needs 1’085 C. It is easy to understand why ancient societies switched to bronze once they found out. A warrior with a bronze sword destroys his opponents weapon. A bronze chisel or axe lasts far longer than a copper tool.
Abundance of Elements in the Crust of our Earth
The problem with tin is that it is very rare. It is 30 times rarer than copper and does not appear in the same geological formations as copper. The relatively soft, silvery metal was first found as oxide in river banks and was extracted from sand the same way we pan gold today. In previous blogs we noticed that copper was abundant in Cyprus and Anatolia. The reddish-brown metal substantially contributed to human development.
Major Tin Deposits : Portugal, NW Spain, Brittany, Cornwalls, Afghanistan & Uzbekistan
Everybody used copper axes and tools. Even Özi, the 5’000-year-old mummy found in Italy's glaciers carried a copper axe. The issue with copper is that it is soft and often needs to be sharpened or re-cast. On the other hand it is malleable – that is why we still use it for electric wires – apart from its high electrical conductivity. There were a few small tin findings in south-eastern Anatolia which is probably how people found out that copper alloyed with tin is superior to the two metals on their own. But these local resources were quickly depleted.
By 1'500 BC, Tin was supplied by a wide, international Trade Network but had to go through many hands and was taxed at every location. It was a fragile supply chain.
Mentioned yesterday the Uluburun ship which sank 1’400 BC off the coast of Kekova and lies in 50 meters depth. It is now exhibited in Bodrum’s Maritime Museum. The ship carried 348 copper ingots, totaling 10 tons and 1’000 kg of tin. There was sufficient metal to make 5’000 bronze swords. Archeologists tried for years to determine the tin's origin. To no avail. The technologies available produced no clear result. In the last few years however, scientists started using isotope analysis to correlate mines and ingots. Thanks to the new technology, they found out that 1/3 of the Uluburun tin came from mines in Uzbekistan.
It took more than 22'000 dives to excavate the Uloburun Ship Wreck from 1984 - 1994
These findings indicate that a sophisticated international trade network already existed 3’500 years ago. Due to the strategic value of bronze, tremendous efforts were made to secure the necessary tin. In the earliest civilizations, tin played the same role as oil in the Second World War. The nations who had it could build superior armed forces. The need for more tin also explains the westward expansion of the Phoenicians about 500 years after the sinking of the Uluburun ship. Through their trading network they must have heard about tin on the Atlantic coast. They established Cadiz as major hub and established settlements on the estuaries in Portugal and NW Spain.
Tin bearing Ore on the Iberian Peninsula
It was tin trading that made the Phoenicians such a formidable power in the Mediterranean. The profits from the trade financed the large fleet and allowed the establishment of far flung colonies on the shores of Africa (Carthage) and Spain. Assume this is also the reason why the Assyrians became so powerful. They not only controlled Anatolian copper but also tin - all Phoenician towns in the Levant were tributary states to the Assyrians.
The Western Tin Trade went through the Hands of Phoenicians and Gauls - Greeks and was a more reliable supply chain than the Eastern Tin Trade
The western tin trade also explains the relative sophistication of Gaul's Celtic population. We know that they were big importers of Mediterranean goods such as wine, olive oil, ceramics and jewelry. It also explains why the Greek were so eager to settle in Marseille and on the French coast around Narbonne. There was a lot of money to be made. Like the Phoenicians, the Greek settlers had ships to transport tin to the Middle East where most of the demand was located.
Model of the Uluburun Ship in Bodrum's Maritime Museum
In the cataclysmic turmoil around 1'100 BC, when Sea People overrun many Empires and reached the shores of Egypt, the trade in tin was severly disrupted. Bronze could not be made any longer. People had to make tools and weapons from iron which was less strong than bronze but was available everywhere. Over time, they learned to forge carbon into iron and to make steel - one of most essential metals to today. Elon Musk's Starships are made with steel. Unfortunatley, we are not allowed to dive on the site of the Uluburun wreck. it is protected, It would be awesome though to see this "high tech" link of antiquity.
The Uluburun ship sank very close to Aperlai (yesterday's blog)
Comentarios