Near Boží Dar numerous well-preserved heaps of waste rock show techniques of placer tin mining that was performed here at least from the 16th to the 18th century. The heaps evidence a wide extension of placer mining in the upper Ore Mountains. The entire placer field covers an area of more than 250,000 square metres, and hence, is one of the largest in Central Europe. The length of a single placer-mound usually ranges between 5 to 10 m with a height of the mounds below 2 metres. They are most concentrated in the area west of Boží Dar along the left tributary of Černá stream and along the watercourse of Černá itself.
Placer mining means to use water in order to repeatedly separate loose alluvial material (sand deposits) into a light fraction and a heavy one. From the latter the tin stone is finally extracted. The light material has been scoured out several times and is free of humus substrate. Consequently, the dumped placer mounds have poor contents of nutrients. Therefore its vegetation markedly differs from that in the surrounding landscape. Typical placer mound vegetation can be seen as heather, cranberries or arnica. They constitute a unique and formative element of the landscape around Boží Dar.