Seven Mountains - Geo Hike: Hühnerberg

In the middle of the Oberhau, almost like a landmark for basalt mining, stands the greenish-painted, highly visible crusher tower of RPBL (Rheinische Provinzial-Basalt- und Lavawerke GmbH & Co. oHG, Sinzig) on the edge of the Hühnerberg basalt quarry. When magma rises rapidly almost unchanged through thin vents and solidifies on the Earth's surface, a very fine-grained rock, a volcanic rock, is formed, here in Hühnerberg basalt. Basalt is mainly used for road construction, as gravel for railway tracks, and as an aggregate, for example in concrete production. As smelted basalt, the rock is used to line equipment parts exposed to heavy abrasion. As can be seen in the adjacent aerial photograph, the quarry has hollowed out Hühnerberg and now reaches 90 meters deep into the ground. If the mountain used to be 362 meters high, the slope edge today is at 289 meters, so 163 meters of basalt have been mined. The operation will continue for several more decades. With blasting, the basalt rock is extracted in six extraction levels with a height of 30 meters, cleaned, and then crushed into various granulations. This ranges to basalt sand, which is used as filter sand or for soil improvement.