Gold was extracted around Roudný as early as the 13th century. The original gold-washing was later replaced by mining technologies. The largest mining boom came at the beginning of the 20th century, and Roudný became the most significant gold mine in Central Europe. The English society Sudgen & Fisher extracted almost 6 tons of pure gold in this locality prior to 1930. The mining went as deep as 450 metres; however as the profits gradually decreased, the mining was eventually stopped during the economic depression. The last works in this area were carried out in the 1950s. Parts of the old buildings are now being used for different purposes, while other parts have disappeared without a trace. The rugged terrain with spoil heaps and remnants of pits with numerous depressions still remind us of the former mining activities. The mostly caved-in tunnels are occupied by bats. Large mouse-eared bats regularly spend their winters in the 300-metre-long Mořic Stole. The steady temperature in the tunnels enables bats to hibernate during the winter period; however they must not be disturbed during hibernation, so the entry to the tunnel is blocked. The Mořic Stole was listed in the National Register of Significant European Localities under the Natura 2000 Scheme as a significant hibernation spot in 2004. Large heaps of processed material, fine silica sand, were left at the Roudné locality. Thus, unprecedented sand dunes appeared in the landscape below the Blaník Hill. The tiger beetle was discovered here in the 1990s, a ground-beetle species prevalent mainly in more southern countries and rare in the Czech Republic. Sand lizards like the ragged terrain and occupy the sunny spots. Pine trees were later planted in the sand pits of the former sludge lagoons and Formica ants now build their anthills here.