The History of Mining. Michael Coulson

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      Georgius Agricola (1494-1555)

      Georgius Agricola is one of the most influential figures in the history of mining. His book De Re Metallica was the core textbook on mining and metallurgy for over two centuries. It remains today a remarkable body of work, both historically significant and an unrivalled description of mining in the Middle Ages and before. In 1912 it was translated into English by American mining engineer Herbert H. Hoover and his wife Lou; Hoover subsequently became President of the USA.

      Born Georg Bauer in Glauchau, Saxony, in 1494, Agricola went to Leipzig University and after graduating in 1518 he taught Greek and Latin in the city of Zwickau. He went back to teach at Leipzig but intrigued by the Renaissance he travelled to Italy where he became interested in science and obtained a degree in medicine in 1526, and where he also became known by the Latin translation of his German name. In the late 1520s he returned to Germany to Joachimstal where he took up the position of town doctor. It was at this time that Agricola became interested in mining, having invested with some success in the Gotsgaab silver mine which provided him with a lifetime income. He made an extensive study of mining techniques and metallurgy in the region around Joachimstal, which was a major mining centre.

      In the 1530s Agricola moved to Chemnitz to take up another medical appointment and it was around this time that his first book on mineralogy, De Natura Fossilium, was published. He continued his study of mining and metallurgical techniques in tandem with his medical practice and began work on De Re Metallica. In 1543 he married Anna, a widow, whom it is thought may have been his second wife. Agricola had at least three children by Anna and reference is made in Joachimstal records to other earlier children.

      During this period he also found time to serve as burgomaster in Chemnitz, a considerable tribute to his standing as he was a staunch Roman Catholic in a Protestant country. He died in 1555 having completed Metallica a few years before and the book was posthumously published a year later. It was his last and greatest work; in total he wrote more than 20 books and pamphlets covering mining, metallurgy, medicine and religion. Anna and at least three of his children survived him and were still living in the 1580s.

      De Re Metallica is comprehensive in its scope, covering hundreds of mining operations that Agricola had observed or studied. The book also includes scores of highly detailed woodcuts illustrating aspects of mining and metallurgy, and some of the first observations on geological strata and how rocks occurred in layers that could be traced for many miles. It is an historic and formidable work that stood the test of time, two centuries in fact, and it remains an invaluable work for studying the mining techniques of the Middle Ages today.

      Silver

      Whilst both England and Spain had historically important mining industries, central Europe was also a key mining area, encompassing the states of Germany and other countries such as Hungary and Italy. In the early 13th century near the city of Schemnitz, 60 miles northwest of Budapest, silver deposits were developed and production may have reached 5 tonnes a year. The mines continued to be substantial producers until the end of the century and other silver mines were established in the region, but Hungarian production declined as the century waned, setting off a period of silver shortages and rising prices.

      The strong silver price also stimulated production in other parts of Europe – for instance silver mining near Coombe Martin in Devon in England was revived. Silver was important because of its critical role as coinage and fluctuating supplies did create considerable problems in terms of financial liquidity, which could lead to substantial fluctuations in price levels if supply expanded or contracted rapidly. It was for this reason that gold became an increasingly sought after metal, and production in the 14th and 15th centuries rose in order to fulfil this role, with mines in Transylvania and Slovakia, then known as Upper Hungary, being developed, with output totalling around 4 tonnes per year.

      Perhaps the most important silver discovery in the 13th century was made near Kuttenberg, now Kutna Hora in the Czech Republic. The find generated a lot of interest and something of a rush developed with some chronicles suggesting that at least 10,000 miners had been attracted to the field; other figures were even higher. At its peak in the late 1290s Kuttenberg produced around 200,000 ozs of silver annually but production soon tailed off, although silver continued to be mined for a further 100 years. Attention then switched to a new discovery in the region at Pribram.

      When output at Pribam faded too, attention turned in the first half of the 14th century to silver deposits much further south on the island of Sardinia where deliveries to the mint at Villa di Chiesa, which ran at just over 200,000 ozs, helped to make trading in the region more liquid. At the same time silver was also coming from areas to the east in Persia and Afghanistan, suggesting not only favourable regional (in the widest sense) geology but also well-trodden trading routes, and continental shortages. This latter situation (as we mentioned above) led to increasing interest in gold mining and the use of gold in coinage, as well as new sources of silver.

      Another problem for European silver miners was the steady fall in silver grade mined over this period, with 100 ozs per tonne of ore common in the 12th century but 200 years later grades of 10 to 15 ozs per tonne were not untypical. Of course grade reduction is something very familiar to today’s miners, and also familiar today is the circle where falling grade leads to falling output, which in turn starts pushing the price back up, leading to a re-examination of the viability of old mining areas. This started to happen in the 14th century in the Balkans where in one case the silver mine at Srebnica in Bosnia that had produced around 50,000 ozs per year in mid-century produced a paltry 5,000 ozs in the late 14th century. As the silver price waxed and waned over the decades silver mining tended to shift away from Hungary to Balkan countries like Bosnia and Serbia.

      In the second half of the 15th century Balkan silver and gold production was disrupted by the invasion and occupation of the region by Turkey. In the following century Turkey’s grip on Balkan commerce weakened, enabling silver mines to sell into buoyant markets, with Bosnian and Serbian production soaring to almost 500,000 ozs in the 1520s. Gold output from central European, Balkan and African mines exporting to Europe was also on the rise and by the mid-15th century had reached 200,000 ozs. However, there was a price for this growth as some of the treatment processes were rather hair-raising, particularly when mercury was used to attract gold and then evaporated off causing air pollution that was dangerous to the health of unwary process workers.

      Lead, tin and copper

      Silver and gold were not the only targets, and deposits of lead, tin and copper were also mined in central Europe during the 13th century, with more copper being found in the Harz Mountains of Germany where silver mining had re-started in the 10th century, tin in Bohemia and lead in Poland. Output, however, began to decline later in the century, and in the 14th and 15th centuries European consumers had to turn to Turkey and the Middle East. The Balkans, Austria and Slovakia also developed copper mines as demand rose in European markets, and these areas became the main suppliers as the 15th century progressed.

      One of the new uses for copper at the time was as copper plate for engravings as the printing industry evolved. At the same time there was a revival of lead and silver output from old mines in England located in the Tamar Valley in South West Devon. Here new pits were dug and old shafts de-watered to re-start mining; for a few years this thrust England back into the picture as an important source of metals. The Devon output was primarily silver, but lead mines further north in Derbyshire provided a flow of that sought-after metal to central Europe.

      German iron ore miners in the Middle Ages in the Harz Mountains using the overhand stoping method

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