At the beginning of the 1530s, rich tin deposits were discovered in the region surrounding the current mining town of Horní Blatná, which were the reason for the town’s founding in 1532. The largest mines were built on the Plattenberg mountain (Blatenský vrch) to mine the Wolfgang and Georg seams. These seams, known as greisen veins, were several metres in width. They were developed both above and below ground from the 16th century until the second half of the 18th century. Among the features that have survived are the Wolfspinge (Vlčí jáma, “Wolf’s Pit”) and Eispinge (Ledová jáma “Ice Pit”) sinkholes.