Mining in Obří důl (Giant Valley) – Part 2
In the 17th century Jacob de Waggi built so called ”poisonous furnace” for processing of arsenic ore in Pec pod Sněžkou. Arsenic was in demand due to its use for wooden hull coating of large transatlantic ships. At that time, it was a coming peak of arsenic mining. In 1836 Ruffer of Wroclaw took charge of the arsenic company at its peak of arsenic mining in Obří důl (Giant Valley). Year production rose up to 50 tons of copper and 120 tons of arsenic. Since 1860s the mining was dwindling. Metal ores were scarce in depths and costs of mining were more expensive. The demand for arsenic continued to fall when the biggest customer Hamburg harbour started covering ship hulls with sheet metal. In 1876 the furnace was put out and it has never been restored since then.
Mine raw materials
Polymetallic ores, especially sulphides such as pyrrhotite (FeS), arsenopyrite (FeAsS), and chalcopyrite (CuFeS2) were of the main interest of historical mining in Obří důl (Giant Valley). They are spatially dependent on each other and contain arsen and copper except from copper. There can be found also sphalerite (ZnS), pyrite (FeS2), galena (PbS), magnetite (Fe3O4) and in particular the low-level presence of stannite. (Cu2FeSn4). It is possible to find also pure bismuth and cassiterite. Regarding non-metallic minerals there are represented garnets such as andradite and grossular; quartz such as purplish fluorite and scheelite. The last-mentioned mineral brought Obří důl (Giant Valley) fame especially among collectors abroad. Scheelite is usually grey white or colourless. Under Sněžka it can be found a rare slightly orange variant. Thanks to the fact that it contains wolfram during 1952-1959 geological survey of the area was carried out. At that time miners built a seven-kilometre-system of tunnels and shafts which partly followed old medieval mines. Wolfram used to use for production of the most effective anti-armour missiles.
Opening of the Kovárna Mine (Smithy Mine)
On July 23rd 1988 speleologists from Albeřice saw the interior of the Kovárna mine for the first time. They saw huge dug up areas, ancient mine equipment, beautiful rock patterns, and waste from the demolished hut Kovárna. Owing to roof stability in tunnels speleologists came with the idea to open a part of the mine to the public. It took five years to collect all necessary documents and permissions of people involved to open it. Among local inhabitants there were several rumours saying that Mining authority drove speleologists out of the mine or Administration of Krkonoše National Park banned from opening it. The last rumour accused miners alone of retaking the mine for themselves in order to sell minerals for huge amount of money on exchanges. The truth was completely different. The delay was caused by estate restitution where the entrance to Kovárna and Barbora mines was planned. It took a while to find out who owns the estate. Then, when it was solved, the contract could be concluded between speleologists and the District authority in Trutnov. All costs for opening the mine were covered by speleologists of Albeřice. It cost them 5 million CZK. In 2004 the mine could welcome its visitors for the first time. Demand for visiting the mine was huge so the speleologists decided to show the most beautiful parts of historical mine during an excursion. Complete opening of mine to the public took place in 2011. The former mine is opened only in summer and yet each year it is visited by thousands of tourists. Moreover, mine tours are fully booked way in advance.