The tin and arsenic ore dressing plant (1933–1945) was the most successful operation of its kind in the western Krušné Hory Mts. The entire mine premises is named after the Otto Shaft, located at its upper end. The spoil heaps in its surroundings contain 75 mineral species including ores of tin, tungsten, arsenic, iron, uranium, topaz, tourmaline, opal and jasper.