Fischbach is one of Luxembourg’s early industrial centres: until 1857, bog iron orefrom the Mersch area was smelted here in blast furnaces. The blast furnace was located in the area of the ponds south of Fischbach. Water and charcoal as energy suppliers were easily available here: the water was impounded in ponds and drove water wheels and bellows. The charcoal for smelting the ore was obtained from the wood in the surrounding forests.
The bog iron ore was formed in the Tertiary, when the rivers had not yet cut into the subsoil. The landscape resembled a slightly undulating plain and the climate was warm and humid. Under these conditions, iron-bearing minerals dissolved from the subsoil. The dissolved iron was transported in the groundwater and solidified in contact with oxygen, e.g. in small ponds, to form bog iron ore. While rivers subsequently cut into the subsoil, some of the ore remained on the plateaus. A large part was washed into the valleys and deposited there.
In addition to Fischbach, the villages of Haller and Grundhof were also historic iron industry sites in the Natur- & Geopark Mëllerdall.
Traces of the past iron industry can be discovered on the hiking trails F1 and F2.