Mining traditions of Krucze Skały

KRUCZE SKAŁY

Mining activities at Krucze Skały started already in the Middle Ages.
According to one version, the oldest adits in the rock were made by Tyrolean miners, who looked for sapphires and gold. This piece of information comes from Wegweiser durch das Riesengebirge, published in 1898.

That event is commemorated on a stone at the tunnel entrance. Adits in the mountains were built in hill slopes and miners tried to reach the secondary, enriched and deeper layer. Mining activities in the 15th and the 16th centuries were aimed at maximum gain with minimum cost. Miners exploited the richest deposits, selecting the largest mineral concentrations. If a deposit was vast, adits were excavated towards the existing shaft or a shaft was built towards the existing adits. In this way, the mine was well-ventilated and it was easy to transport the excavated material to the surface. Tunnels were built along the main vein. When it disappeared in the roof or in the floor, blind tunnels were drilled upwards or downwards. Adits were constructed every 15 meters with tunnels, 2 m high, which gave access to mineral concentrations. Ore was sorted inside and then it was carried to the surface. Waste rock was left at the mine face, where it was placed along the walls and inside unused, exploited chambers.
In Schlesiche Provinzialblätter of 1797 there is a piece of information concerning a Gottfried Exner, who in 1788 or 1790, apparently established two kaolin mines. Not only kaolin was excavated in the Karkonosze Mountains, but also feldspar, because after processing it, one could get kaolin, which was indispensable for the production of high-quality porcelain.
It was rumoured that Gottfried Exner received 20 francs in gold for one tonne of kaolin. Kaolin was sent to porcelain manufacturers in Berlin.
Feldspars are one of the most common minerals. In igneous rocks, like granite, they constitute 50% of the whole mineral content. A distinctive feature of the Karkonosze granite is the presence of pink feldspars, which one cannot find in granite from Strzegom or Strzelin. They are usually pink 1-7 cm tablets in the form of very delicate, well-arranged, shiny layers.
Traces of Gottfried Exner’s activities at Krucze Skały can be seen even today. There are two artificial caves at the foot of the rocks.
The rocks are not only famous for their feldspar and kaolin deposits, but first of all for pegmatites, sapphires and garnets.
In granite there may be coarse-grain vein rocks called pegmatites. Once the main magmatic mass becomes solid, thanks to the presence of volatile matters, quartz, feldspar and muscovite can crystallize to huge sizes as overgrown, intermingled crystals. Among them one may find corundum, tourmalines, amethysts, topazes and minerals containing trace elements like beryl.
Corundum is a form of aluminium oxide and is very hard (9 in the Mohs scale of mineral hardness). Only diamond is harder. Pale blue, 5 cm crystals of corundum have been found at Krucze Skały. Corundum can be red, dark blue, light blue, pink, brown, violet, grey, black or even colourless. Metal dopes determine the colour.
Transparent types of corundum, called sapphires and rubies, are precious gemstones. The pegmatites of Wilcza Poręba contain a few centimetre large crystals of white or pale blue sapphires.
The most valuable sapphires found at Krucze Skały in the late 19th century are now on display at the Geological Museum in Wrocław.
In autumn 2002 the last pieces of sapphire were found in the material excavated by the former kaolin mine, at the foot of the two adits. One of them was a beautiful blue sapphire that was just a small projection on pegmatite and its base was about 10 mm.

In ancient Greece, sapphire was devoted to Zeus. Cleopatra wore one in her crown. People have always attributed extraordinary characteristics to gemstones. Sapphire was thought to have made people calm, virtuous and pious. In the Middle Ages monks and priests wore it, as it was supposed to revive bodily strength, help people to get rid of spite and unfaithfulness, set people free of darkness, bring courage and help to conquer enemies (at that time it was called the ‘stone of victory’).
Especially powerful was the ‘star sapphire,’ as lines crossing within it symbolized faith, hope and destiny.
Walking along the Płomnica that flows at the foot of Krucze Skały, one may find some garnets in the riverbed. The name garnet may come from the Middle English word gernet ‘dark red’, or the Latin Punica granatum ‘pomegranate’, a plant with red seeds similar to some garnet crystals.
Garnets were particularly popular in the Middle Ages and because of their red colour they were called carbuncles (from Latin ‘glowing coal’). Anselmus Boëtius de Boodt, official physician of Emperor Rudolph II, believed that garnets were formed out of water drops that were dyed with blood just before drying. He also mentioned a garnet in possession of Rudolph II, which was as big as a pigeon’s egg. Red garnets were thought to have been magical – the more crimson a gem was, the more treacherous, as it contained deceitful fire. Garnets protected its owners from pestilence and thunderbolts, they revived vigour, protected from infamy, gave strength to make decisions, devote oneself to ideas or make sacrifices for a beloved person. According to popular medieval belief, garnets ground to powder were effective medicine for different disorders.
It is worth visiting Krucze Skały and looking for beautiful sapphires or garnets. Perhaps the Lord of the Mountains will be so kind and let you find some of the hidden treasures.