„Glück Auf!“ in the historic mining area Schwarzleotal!
The sparkling and colourful ore minerals has always inspired and fascinated people. The discovery of ores and ways of processing and treatment led to a new chapter in the cultural and technical development of mankind. Curiosity and courage of our ancestors were the key to the civilisation, as we know it today.
Archaeological findings have show that already 1500 B.C people looked for ore in the Schwarzleotal. As chance – in this case called plate tectonics – would have it, the area was rich in precious minerals. From medieval times on until modern times mining was operated in the valley and laid the foundation for the development of the village Leogang.
The mining activities attracted not only miners to settle in this area; also craftsmen moved to the region. They supplied construction material for the tunnels and building as well as tools. Furthermore, the processed ores and extracted precious metals. Additional, scholars settled and took care of administration and management.
The history of the mining can be experienced firsthand in the Schwarzleotal.
A living settlement
Today, the Schwarzleotal enchants with its naturality, but it was once a colonized and economic active valley. The settlement consisted of mining-associated buildings (administration and processing) and miner’s homes. During processing the ore was separated from the waste rock. Some foundations have been preserved, some are only known from historical maps of the area. On a walk through the scenic Schwarzleotal you can learn more about the processing of ores. New technology returns even ancient buildings back to their places.
A trip into the past
The Barbara tunnel and the Daniel tunnel are accessible today as show mine. A guided tour brings you back in the 15th century. Experience the world underground and learn more about how the miners proceeded to gain the ore.
Since 2021 the show mine can be visited barrier-free. Visit the website www.schaubergwerk-leogang.com and experience the mine virtually.
Hammer and anvil
In mining areas the demand for iron tools and building materials was high. Therefore, an own blacksmith was directly on site. In the Schwarzleotal, the blacksmith was located in front of the Erasmus tunnel. The old foundations are still preserved. The forge stone inside the wars is made of granite, which is an ideal material for forging due to its robustness. Granite does not occur natural in the area around Leogang. Hence the stone has probably travelled far to find its place.
In the blacksmith shop pokes, hammers, various iron tools, picks, wedges and countless other necessities were forged. The miners received their tools in the so-called “Unschlitthaus”. Each miner had his own personal working tools.
Sustainability was a top priority even back then. If a tool was damaged, the blacksmith was available daily to mend or repair the tool. Thus, resources were conserved, and no disposable products were produced.
Making the past visible – Ground penetrating radar
Time let the grass grow over a lot of things. Sometimes even a forest. Buildings are ephemeral and in the course of decades and centuries they disappear from earth’s surface. Modern methods allow us to look under the grass without destroying surfaces. In archeology and construction industry, the ground penetrating radar (GPR) is used to investigated the upper part of the earth’s surface. It can be used to find old foundations, cavities or pies or to determine quality and thickness of ice and snow covers.
The ground penetrating radar emits electromagnetic waves that are reflected and returned at material boundaries. This is due to the difference in rock or material properties. The received waves produce an abstract image of the subsurface that can be “translated” by geophysicists.
The power of water
From historical maps and illustrations around 1800, it is known that a water powered elevation system was used in the Erasmus tunnel. Illustration of source containments and water tunnels on maps suggest the use of the nearby running waters.
The elevation system was used for ore transport between the different tunnel levels. Water was guided into the mine through tunnels. Water wheels operated a reel to lift the mined ore from deeper levels. The water was discharged again in a lower-levelled tunnel. In addition, the system was used for dewatering the tunnels. Water seeping into the tunnels from fissures in the rock, could be drained to keep the mine “dry”.
The construction of the water powered elevation system required a lot of technical understanding. A construction plan from 1795 shows “a new winding machine” indicates the technical achievement of this time. To calculate the amount of water and the gradient of the water paths were crucial for the functionality of the system. The power was transmitted and amplified by the arrangement of water wheel, gear wheels, transmission shafts and pulleys.
This technical achievement eased the miner’s work and increased the economic efficiency of the mining district.
The Erasmus gallery is not accessible anymore. Therefore, more detailed investigations and information about its construction. Functioning and water flow are not possible and will probably remain a secret of the historical mining are in the Schwarzleotal.
The Schwarzleotal has a great diversity in ores and mineral deposits. Archeological finds have shown that this area was already known to the Celts in the bronze age (1500 years BC). The mines were active between the 15th and 19th century. Minerals containing silver, copper, nickel, cobalt, mercury and lead were mined here and contributed to the development of the region. However, the story begins much earlier.
Austria is geologically very diverse. Several orogenic events, the crumpling and lifting of the earth’s crust, have brought together different types of rock in a very small area. The colourful geological map of Austria reflects the geological diversity in an abstract way.
The formation of the dolomites and slates in the Schwarzleotal began about 440 million years ago: During that time, an ocean developed, and sediments were deposited in the evolving basin. At the same time, volcanic activities along plate boundaries led to the deposition of volcanic rocks within the sediment. During the Variscian orogeny about 350 to 300 million years ago and during the Alpine orogeny 80 million years ago – mountain ranges were created due to converging plate tectonics. These processes led to stacking, folding and thrusting of the involved sediments and rocks.
The high pressures and temperatures during the orogeny changed mineral composition, texture and properties of the rocks. Rocks transformed under such conditions are called metamorphic rocks. Slates, phyllites and dolomites formed from the original sediments.
The mineralization and deposits in the Schwarzleotal were formed during different geological periods. Volcanic activities in Silurian/Devonian times led to the enrichment of nickel and cobalt in the sediments. During the Variscian orogeny, metal compounds were dissolved, re-mobilized and finally concentrated in mm to cm thick ore veins. The copper-bearing ores accumulated along faults and fissures within the dolomite during the Alpine orogeny.
Moving a mountain
Thanks to busy accountants, we can roughly comprehend, how much ore was gained in the past centuries. For a better understanding, the historical units were translated into the metric system. From recordings of the year 1715 we know, that 1 Zentner ore contains 11 Pfund copper and 1 Loth silver. Expressed in today’s units this are 56 kg ore, 6,2 kg copper and 17,5 g silver.
The metal concentration in the ore can vary significantly. Hence, it is hard to estimate, how much tons of ore had to be mined to gain a sufficient (economic) amount of a metal. The total amount of rock, including the waste rock, was a multiple of the gained amount of ore. We can conclude that they had to move mountains to get small amounts of valuable metals.
The extracted ore bearing rocks from the mine were crushed and milled to sand size or even smaller. In the mine washery, the fine-crushed and milled material was subsequently sorted by the power of water. The separation of ore and waste rock was performed mechanically using water and gravity. As or has a higher density than the waste rock, the useless rock material was washed away by sponging processes. Water was directed into slurry trenches and washing tables. The lighter waste rock was easily washed away by the flowing water. Only a sludge of ore remained in the trenches/tables. This sludge was subsequently dried over fire and then transported to the smelting furnaces for further processing.
The art of ore preparation
During the work in the tunnels the miners couldn’t yet estimate with certainty the values of the mined ore. They could determined mineralized zones and also the weight of the rocks gave a hint on ore content. But they could not tell which metals and which amounts of the metals were hosted by the rocks. The mined ores were investigated and tested in the so-called “Probierstube” to determine the economic value of the ores and to choose appropriated processing methods.
In this testing stations only small amounts of ore were evaluated. In small ovens the ores were melted. This work required sensitivity and precision, because the determined processing method influenced the quality of the ore melts and also the economic value.
The rocks were burned, washed and crushed. These steps varied depending on the hardness of the rock. Soft rocks were only crushed, hard rocks were burned to make them friable. Subsequently the prepared fine-grained ores were roasted in the closed vessels.
The separation of the individual metals took place in the testing ovens using additives. These additives were mainly other metals or rocks to change melting temperatures and induce chemical reactions. Besides the already mentioned additives also curiosities found their way into the secret recipes: rusty iron, salt, vinegar, tartar and even urine and grounded deer antlers are listed. To extract the metals a lot of knowledge and experience were necessary. To know how difference elements react with each other was the key to success. Today, this is much easier, as we know about the chemical properties of elements. Nevertheless – even today we cannot completely avoid experimenting and testing.