For centuries people have been tantalised by the allure of shipwrecks. The drama and the tragedy of ships lost at sea has captivated people, as has the possibility that those wrecks might contain vast amounts of valuable cargo. Salvages have been drawn to wrecks throughout time, but what is the reality of these shipwrecks? Are there vast amounts of gold and silver waiting to be found at the bottom of the oceans? And, if there are, who owns them?
A late-fifteenth-century Ryal of Edward IV, of the sort found on the wreck of the Mary Rose. Valued at ten shillings, this gold coin was struck during the immense turmoil of the Wars of the Roses.
A 1797 Cartwheel Penny of George III, struck in copper by Matthew Boulton’s Soho Mint. Coins of this sort were found on the wreck of the Mary Rose despite them being struck centuries after its sinking.
Cowry shells like this come from sea snails, and were historically used as a form of currency in parts of Africa, Asia, the Americas, and Oceania.
During excavations on Henry VIII’s flagship, the Mary Rose, fragments of leather and the handle of a money changer’s bag were discovered. This would have belonged to the ship’s Purser, responsible for ensuring all wages were paid, keeping the ship’s accounts, buying supplies, ensuring that rations were properly distributed and money changing.
Artefacts like this archer’s wrist guard were among those found on the wreck of the Newport Medieval Ship, and are used by conservators and historians to interpret events of the past. Image courtesy of Newport Museums and Heritage Service
These special 2014 1/4oz Britannia coins were struck by the Royal Mint in silver recovered from the wreck of the SS Gairsoppa, a British steamship that was sunk in World War Two while carrying over seven million ounces of silver bullion.
Our guests in this episode were Kate Rogers (HM Coastguard), Dr Alex Hildred (Mary Rose Trust), Dr Toby Jones (Newport Ship) and the Dr Eric Nordgren (Cardiff University). Click here to find out more about them.
Like all items exposed to sea water, coins will corrode after sufficient exposure time. Think of the sea as a kind of chemical soup, which is largely made up of water, salts and a small percentage of organic material. When a coin falls into this mixture it will react with these chemical ‘ingredients’ around it and can easily breakdown through a process called corrosion. Factors such as the temperature of the sea water will make a difference to how the coins react. Warm water is generally saltier than cold water this means chemical reactions happen faster or more frequently. Some areas of the sea are also ‘anoxic’ or very low in oxygen. As oxygen is needed for a lot of the chemical reactions we see when metals rust and degrade, coins that fall into anoxic environments can be very well preserved.
Some metals are more reactive than others and will corrode quickly due to the salts suspended in sea water. Other metals are not reactive at all and stay in the same condition for hundreds or thousands of years. Pure gold is well known for its resistance to corrosion, and a pure gold coin is unlikely to degrade at all and can sometimes be found at the bottom of the sea in pristine condition. Silver will have different types of corrosion form, which can sometimes look like a thick crust forming over the coins, caused by salt in the sea forming silver chlorides. Coins that have these thick crusts are commonly known as ‘biscuits’.
Base metals react in all sorts of ways. Copper can last for a long time in the sea but you will often see these coins turn green, where salt in the water reacts to produce copper chlorides which are a characteristic green. Whenever you see this green corrosion it is a good indication that the item contains copper, like the Statue of Liberty. Metals like iron and even more reactive modern metals like aluminium or magnesium, tend to corrode very, very quickly but fortunately for maritime historians, coins don’t tend to be made of these materials.
Coins are very rarely made of just one metal. Most coins are made up of an alloy, a mix of two or more different metals. Even gold coins contain different amounts of metal such as copper or silver, coinage bronze is a mixture of copper, tin and zinc. As a result, corrosion of coins in the sea can be very complex.
Coins that are recovered from the sea are treated with special conservation techniques to stabilise them. When coins are submerged for a long time they become used to that environment. Suddenly bringing them into a different environment can have a big impact, because the kinds of chemical reactions that would happen when you bring things into the air is quite different than those that take place underwater. There will usually be a lot more oxygen available for chemical reactions and objects might start to dry out. This can cause coins to corrode very rapidly and disintegrate completely if they are not treated correctly.
Conservators can often be found at an excavation assessing the condition of things as they are found, keeping any fragile objects supported until they can be treated. Once coins from a shipwreck are on shore in the conservator’s laboratory the real science can begin! Conservators can use scientific methods such as x-rays and microscopy to study the coins and decide on a treatment plan. Careful cleaning might take place as coins are often fused together or covered in corrosion products. Most coins will be gradually transitioned to fresh water to remove salts from the seawater that could cause them to degrade further in the air and finally they will be gradually and carefully transitioned to a drier environment. Once the coins are dried out and any further treatment like coating or consolidation has been carried out, it is the conservator’s job to get them into the right type of storage so they can be held safely for future study or display. All of this information is also passed back to the historians and specialists working the wreck, to help them build a bigger picture of the archaeological site.
Raising the Mary Rose - ITN news
'Seabed to Showcase' the story of the money changers purse
Information on the crew of the Mary Rose
Information on the Newport Ship
‘The Battle About Money’. An engraving of 1570 by Pieter van der Heyden, of a painting by Pieter Bruegal the Elder, in which a money changer’s purse is depicted.
Episode 6
Pirates, privateers and general rogues of the sea have been long associated with chests overflowing with coins. But did they really make their fortunes in shining silver, and are there chests of treasure out there waiting to be found?
Episode 1
Whether in warships or life saving, Britain’s naval heritage has had a lasting impact on its currency for centuries. In this episode, explore the story of British naval history through coins of the past.
Episode 2
From pub signs to punk art, the robed and armed female figure of Britannia permeates British identity. Find out how this Classical figure developed through coinage and medallic art to become a figure of the nation.
