The sparkling blue-grey crystals of the lead ore can rarely be found embedded in the white-grey quartz. Galena was the reason why people settled in this area in the Middle Ages, and this is why the village of Altenberg was later named the Lead Town by the Emperor and elevated to the status of a town. We can compare each vein deposit to a leaf that is vertically embedded in the earth. The space between the “leaves”, which are a few centimetres to a few decimeters wide, is filled with a crumbly slate, mica slate. While the slate is an ancient rock, it is 360 million years old, the glittering galena vein deposits are around 140 million years younger. After centuries, the tunnels were buried and depressions appeared on the surface. This can also be seen in the tunnel on the steep mountain north of here. The tunnels are revealed by the deep crevice that leads down into the valley.