Staré Sedlo - Holy Trinity mineral plant

Nature and Technology in the Ohře Valley

The occurrences of brown coal and kyze in Tertiary sediments represent the raw material base for the development of industry in the Sokolov region. Coal was initially not used as a fuel, but as a chemical raw material. In 1573, the existence of the Svatá Trojice mineral plant near Staré Sedlo was first mentioned, the oldest factory for the production of alum, sulfuric acid and green shale in the region. The John the Baptist adit was dug to extract the raw material and drain the mines, which is now a cultural monument.

Ceramic vessels used in chemical production in mineral plants. Exhibition of the Sokolov Museum

The Holy Trinity Mineral Works in Staré Sedlo was founded in the mid-16th century. According to the entry in the Falknov town book, the plant was in active operation in 1573. Alum was first extracted, and later also feldspar and vitriol stone for the production of fuming sulfuric acid (olea). Human urine was first used in the production of alum, collected in the surrounding area in barrels and taken to Staré Sedlo for processing. However, when the plague raged in this area in 1582, the population rebelled against this unhygienic order of the authorities. Production then switched to kyz schist, which was abundant in the area.

At the beginning of the 19th century, the Sokolov region became an important center of the Czech stone industry. There were two mineral works in Staré Sedlo, which became modern industrial plants thanks to the industrialist Johann David Starck (1770-1841). The lower mineral plant of the Holy Trinity stood at the Jan Křtitel adit on the right bank of the Ohře River. Pyrite coal with pyrite was loaded into it by carts from the adit. Sulfur was obtained from part of the material by burning in blast furnaces, the rest was piled up in piles, where, due to weather conditions and sprinkling with water, the pyrite rock decomposed into acidic clay, from which sulfate leachate was obtained for production.

In 1888, sulfur production ended, and in 1896, alum and green shale. In 1899, the operation was abandoned and the equipment dismantled. In the period 1902-1945, the plant burned a polishing red called poteé, which was largely exported to Bavarian and Prussian grinding mills and glass workshops.

In the deep and landscape-valuable Ohře Valley, there are significant geological profiles with pseudokarst caves and a paleontological site of Tertiary flora. In total, over two dozen rock cavities are known on both sides of the valley, the largest cave, Cikánka, is over 40 meters long. The area is protected as the Ohře Valley Natural Monument.

The entire area is adjacent to the cycle path from Loket to Královské Poříčí, which can be reached by a suspension bridge over the Ohře River.