Dr Robert Sturm (Austria)
Exploitation of gold deposits in the Hohe Tauern, in the Central Alps of Austria, has a long history: occurrences of this noble metal were explored for the first time about 2,000 years ago. Since the fourteenth century, the search for gold has been conducted on an industrial level, resulting in the production of 130km of tunnels and shafts, with the main centres of medieval gold production being the Gastein Valley, Rauris, Heiligenblut, Fusch and, later on, Schellgaden. In the second half of the fifteenth century, all of the gold found in the Central Alps was sold to Venice, but from the year 1501, the noble metal was exclusively used for indigenous minting and, therefore, all gold mines came under the archbishop’s control.
The economic zenith of gold exploitation in the Central Alps was reached in the middle of the sixteenth century. At this time, three families – the Weitmosers, Zolts and Strassers – dominated the mining industry in the Gastein Valley and in Rauris. In 1557, 830kg of gold (corresponding to about 27,000 ounces) and 2,723kg of silver were hauled from the mines. However, 50 years later, gold mining ceased completely. The main reason for this economic collapse was the total exhaustion of all lodes of ore that had been exploited in the Hohe Tauern until that time.
Furthermore, only ‘visible’ gold (that is gold which is recognisable with the naked eye) was separated from the host rock. Since the development of new gold deposits was accompanied by enormous risks, financial costs and technical problems, these great families turned their backs on the mining business and acted as great landowners or as servants of the monarch instead. In addition, it is currently thought that the expulsion of protestants under the Habsburg emperor, Ferdinand I, and the spread of glaciers to lower altitudes, as well as gold imports from America may have been additional reasons for the closing down of the gold industry in the Hohe Tauern, but I believe these arguments lack any solid evidence.
In the nineteenth and early twentieth century, and especially during World War II, the presence of gold in the Hohe Tauern was investigated again, but mining costs exceeded the output of gold by a factor of ten. This phase of gold mining in the region is inseparably connected with Karl Imhof, who founded the mining company, Radhausberg. From 1938 to 1945, mining was carried out by another company, Preuß-AG, which was, among other things, responsible for the production of new tunnels in Rauris and the Gastein Valley, the latter of which now serves as sanatorium for rheumatic patients. After World War II, the central-alpine region became a favourite tourist destination and still enjoys great popularity today. This has resulted in the foundation of the Hohe Tauern National Park, which is one of the most important nature reserves in Europe.
How was the Tauern gold won?
In the past, gold from the Hohe Tauern was extracted in two ways. While in the Gastein Valley and in Rauris, gold was primarily exploited by underground mining, at other locations in the Hohe Tauern, the metal was also found using washes. However, the washing of gold was profitable in only very few cases.
In contrast, underground mining in the Radhausberg (in the Gastein Valley) was rather lucrative, because, as well as gold, silver was also found in valuable quantities. In the Rauris Valley, exploration for gold (and silver) was mainly located at Hohe Sonnblick, where Ignaz Rojacher was the owner and director of a gold mine. (He was also the constructor of the Sonnblick observatory, 3,105m above sea level, the highest meteorological station in Europe.) Further occurrences of gold that were explored by underground mining were situated at Schellgaden, as well as in Gmünd (Upper Carinthia).
The washing of gold started in the early eighth century AD, when people searched for the metal in the sandbanks of the River Salzach, which is the main waterway of the Central Alps, in the county of Salzburg. According to ancient sources, the washing of gold became a favourite sideline of the rural population living in the central alpine valleys. However, in the thirteenth and fourteenth centuries, hundreds of gold-washer houses were built along the rivers, where single working processes of gold separation from the sediment were carried out.
In the fifteenth century, gold washing also covered the eastern parts of the geological feature known as the Tauern Window (in which high-grade metamorphic rocks of the underlying Penninic nappes crop out, caused by a large dome-like antiform in the nappe stacks of the Alps) and, therefore, reached its zenith. Licenses for gold washing were mainly bestowed on peasants and poor labourers, who made a bare living with their small incomes from this gruelling work.
However, from the sixteenth century onwards, the number of licenses for gold washing diminished continuously and, in the twentieth century, the industrial extraction of the noble metal from washes ceased completely. The decisive reason for this development was a successive decline of gold in the sediments of the central alpine rivers and brooks.
The future of the Tauern gold
For about 30 years, mineralogists visiting the old gold mines of the Hohe Tauern have sampled the gold-bearing rocks and have repeatedly asked whether it would be worthwhile reactivating one or more of them. One of the most promising locations for this is a small arsenic pit near the village Rotgülden. In a side-tunnel (referred to as a ‘gold shaft’), mineralogists encountered a mineral assemblage consisting of pyrite (FeS2), chalcopyrite (CuFeS2) and Quartz (SiO2), which already included a touch of gold. In a deeper part of the tunnel, the scientists discovered a wall of massive ore covered with a crust of red iron-oxide (Fe2O3). Subsequent investigation of this ore in the laboratory came to the surprising result that one tonne of the ore here contains 128g of gold (128ppm), which has to be classified as ‘peak value’.
In 2007, the government of Salzburg gave permission for sample drillings and blasts to evaluate the range and abundance of the gold deposit. However, mineralogists and geologists had already formed the opinion that the 700-year-old mine of Rotgülden contains a rich vein of gold, which is worthwhile for industrial exploration at any time.
Driven by the continuously increasing gold price, the British company, Alpine Metals, and especially its Austrian subsidiary, ORD Resources, carried out the sample drillings noted above. Three years later, a company named Noricum Gold AT GmbH acquired the mining rights for the arsenic pit of Rotgülden and all rights of exploration. Further sample drillings resulted in a gold content varying between 1g and 30g for each tonne of host rock (1 to 30ppm). As calculated by the mining company, profitable gold exploration in Rotgülden occurs at only an average gold content of 10g for each tonne of host rock and the availability of huge amounts of ore. In February 2008, when the price for one ounce of gold amounted to €610, extracting 200,000 ounces of the noble metal was evaluated as being very lucrative.
What is the current situation?
In the summer of 2011, the gold price exceeded €1,300 (US$1,900) a troy ounce for the first time and this price level was maintained for nearly two years. Since the early part of 2013, this record price has significantly decreased and has temporarily fallen below the €1,000 level. These developments show very clearly that the price of gold is subject to partly unpredictable fluctuations, which makes any profitability calculation for the Rotgülden mine rather hard. However, experts take the view that the arsenic pit contains a minimum of 100,000 troy ounces of gold, which would result in total returns of about €110,000,000. However, this would only be achieved if gold exploration is carried out with a close to 100% efficiency. Meanwhile, the ambitions for gold exploration in Rotgülden have increased again and several mining companies are currently trying to find a low-cost/high-profit solution to prospecting for this noble metal.
|Facts about gold|
|Gold was among the first metals to be smelted by man.The exploration of gold probably started in the Chalcolithicum of India, about 6,500 years ago.The first gold coins were minted in the sixth century BC.The largest output of gold is produced in China (355 tonnes in 2011). 40% of the globally explored gold comes from South Africa, the USA, Australia and Russia.The average content of gold in the earth’s crust amounts to 0.004ppm.The deepest gold mine is in South Africa, where the metal is extracted 4,000m below the surface of the earth.Gold has only one natural isotope (197Au).|
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