It's volcanic opal that you can dive deep into here. I wish them luck. People seem fascinated with gemstone mines.
Abstract:
The northern part of the Slanské Vrchy Mountains, in Slovakia, within the territory of Dubnik Opal Mines, is considered to be the historical source of opal, including the opal known to the Romans. Dubnik precious opal mineralization originating from post-magmatic hydrothermal fluids based on its values should be recognized as an area of global importance. Geological processes that are connected to Neogene volcanic activity took place in the territory of the Dubnik Opal Mines and resulted in the formation of various geological products and processes represented by polymetallic mineral formation, opal formation, antimonite formation, and mineralization of the supergene stage, as well as the stratovolcano rock environment, which are of geoheritage significance. Remnants of intensive mining activity that took place during the past 2000 years provide opportunities for visitors to explore, study, and appreciate this unique geological heritage of international importance.
Here is the proposal to improve the traffic of tourists, whatnot. Geoheritage of the Precious Opal Bearing Zone in Libanka Mining District (Slovakia) and Its Geotourism and Geoeducation Potential More than you expect there geologically. I almost put this entry in the mining section! https://www.mdpi.com/2006386
In the mountains Slanské vrchy village called Zlatá Baňa and the village Červenica are famous Slovak opal mines. Opals from opal mines in Slovakia are highly valued on the world market for their unique properties. Their advantage is the so-called opalescence, which means a perfect match of colors. The Slovak mines lived their best times from 1845 to 1880, when they were run by the Viennese jeweler Solomon Goldschmidt and his heirs. The Goldschmidts managed to bring opals to world markets, which gained their fame.
The beautiful opal mines of eastern Slovakia are admired all over the world and have now become a valuable technical monument. Navicup audio tour guide app - Gateway tunnel JOZEF and surroundings, sightseeing, hiking trails etc. https://navicup.com/object/slovakia-gra ... -238076/ba