during the Roman occupation of Spain the mines were extensively exploited. With the fall of the Roman Empire there was no further reference to mercury mining in Spain until 711, when the Arabs overran the country and operated the mines until their departure in the 12th century. The mine then came under the control of the Spanish Crown. In ancient times mercury was used as an elixir of life and even as a treatment for broken bones, later it was used as an ointment and in cosmetics. These are all uses that, bearing in mind the great toxicity of the metal, seem curious to modern minds.
The conquest by Spain of Latin America in the 16th and 17th centuries led to a massive boost in Almadèn’s fortunes as the discovery of particularly silver, but also gold, deposits led to a major increase in demand for mercury as an amalgam to separate precious metals from their ore. Although presenting grave health risks to workers who operated the treatment process, the demand for Almadèn’s mercury in Spain’s New World colonies rose materially. By the 18th century, local mercury was being used to treat Latin American precious metals but Almadèn continued to prosper on the back of Spanish demand, indeed to such an extent that the Spanish government used the mine as a guarantee in receiving loans from, in particular, German financiers in the 16th and 17th centuries. Later the Rothschilds made similar loans to Spain backed by Almadèn.
With the advance of science, mercury found new uses in inventions such as thermometers, barometers and even in dentistry for fillings. In the 20th century it also was used in a wide range of chemical products and munitions. More recently its use in many of these areas has been phased out as governments have become concerned about its safety, but ironically the development of energy-saving fluorescent light bulbs has led to a recovery in mercury use.
As to Almadèn, it prospered in the 1940s when production reached over 80,000 flasks per year but things became more difficult after the Second World War and the mine was re-organised by the Spanish government in the 1980s, only for it to close in the early years of the new millennium as mercury demand fell away. It is calculated that over history the Almadèn mine has produced around one-third of all the mercury ever produced, and the Spanish government is seeking UNESCO World Heritage Site status for the mine.
7. The Lure of Africa
A considerable amount of the precious metal trade in the early Middle Ages between Europe and Africa occurred in the Mediterranean region, reducing the need for Europeans to travel to the African continent. However, although the European colonial surge into Africa still lay some centuries ahead, there was a thriving slave trade going on between West Africa and the Middle East at this time, and African riches, particularly in gold, were becoming quite widely known to the traders from the Middle East. The mines were primarily in the Sudan and West Africa and the trade routes, which carried the gold to Europe, crossed the Sahara. The routes going east to supply traders from Egypt went in the direction of what is now Somalia. During the Middle Ages the trading routes and thus the sources of gold were prone to change caused by material alteration in climate in the region due to temperature and rainfall fluctuations.
Many of the West African gold operations were alluvial, where indigenous miners panned the River Niger and its tributaries for gold as the waters swept down from the mountains of Sierra Leone. This area was a significant source of gold and some gold veins were sufficiently rich to warrant exploitation by shaft access. Other alluvial workings existed along the River Senegal as it wound its way to the Atlantic from its source in Mali. Mali is now one of Africa’s largest gold producers and there is evidence from tools and pebbles discovered close to the operating Syama gold mine at Tembelini in the 1990s that there were gold diggings in the area in the 15th century. Although official figures for regional output do not exist, there is data relating to the value of gold trading, and in the 15th century gold passing through the Sudan amounted to between 30 and 50 tonnes per year.
In the 10th century copper mines were opened up in the Atlas Mountains area near Sijilmasa in Morocco, fairly close to what is now the border with Algeria, and the ore from those mines was treated at Igli in Algeria. That output was exported south to West Africa including Ghana – a rich kingdom and another major source of gold, known as the Gold Coast at the time – and east to the Sudan. Two of the bigger copper mines in the region were Tihammamin and Ten Oudaden. There was another important copper mine at Takkeda, situated in the Kingdom of Mali, whose product was also exported all over the region and to Egypt. One of the most important cities in Mali, which acted as a key entrepot for trans-Saharan trade, especially in gold, was the legendary Timbuktu, which as well as a commercial centre was also a centre of the arts and learning.
The main gold mining areas of Ghana were the Akan states in the southern half of the country, such as Asante, home of the modern Obuasi mine, and Wasso, now home of the Tarkwa mine. There is evidence that gold was being mined by indigenous Ghanaians at least as early as the 12th century and when the Europeans began to make landfall in West Africa from the 15th century onwards they found a thriving gold mining industry in Ghana. Over the next three centuries European traders regularly visited the Gold Coast to trade in the metal. With the coming of the Industrial Revolution and the colonial rush for Africa indigenous gold miners were slowly pushed aside as European miners began to apply new technology to developing mines, allowing them to mechanise their process and sink deep shafts to access rich ore that lay at depth.
Much of the gold and copper mined in the Middle Ages was used as coin, and supply levels could, of course, have a profound effect on the price of both the metals when traded for goods. Also, in stark contrast to today’s world of money printing, coin in circulation could fluctuate materially over time, which could have a serious, usually uncontrolled, effect on local economies. When metals were in short supply coins either had to circulate faster, with inflationary implications, or if they circulated too slowly, sometimes due to hoarding, then economic activity dropped. As gold and silver flowed backwards and forwards between Europe and Africa during the Middle Ages the economic fortunes of trading countries such as Egypt, Syria, Hungary and Italy waxed and waned.
Producing regions were not spared in this process either. We can take an example from the mid-15th century when a shortage of mercury, which was key to the treatment process for gold, developed in Spain, causing severe economic pain as gold production slumped. This not only hit economic activity in both Europe and Africa but also led to debasement of the currency as precious metal content in coins was reduced to allow more coins to be minted.
8. The Opening up of North America
Elsewhere we have talked about the discovery of ancient workings of copper in the Michigan Peninsular of the US and drew attention to the paucity of provenance as to who developed the workings and when. The earlier explorers who arrived in North America came across plenty of evidence of use of stone and metal for weapons and working implements such as axes and knives.
Copper artefacts and even jewellery were also found, suggesting that American Indians were able to work metal but that the raw material was native copper, mainly found lying on surface, suggesting no mining tradition amongst the continent’s indigenous people. Indeed Sebastian Cabot and Giovanni Verazzano came across Indian women wearing copper when they landed in Newfoundland and Nantucket Island respectively around the turn of the 15th century. These sightings of copper continued as explorers continued to probe the east coast of North America over the following centuries.
The Spanish arrive
The vastness of what is now the continental USA meant that without disturbing what was going on in the northeast explorers entered the dry wastelands of the southwest from the Caribbean and Mexico; these visitors were of course the rapacious Spaniards (of which more later), as ever searching for gold and silver, and later we will look at their activities in Latin America. However, in the 16th century from their base in Mexico, Francisco Coronado, Alvar Vaca, Antonio Espejo and Juan Onate all led expeditions north into what are now Texas, New Mexico and Arizona.
Rumours had circulated of gold in large quantities and Espejo headed into Arizona driven by a story of a lake of gold; whilst this proved far-fetched he did stumble across gold in rich veins near what is now Prescott, and this was followed by the arrival of Onate to stake claims in the area. This did not lead anywhere as it proved impossible