Fossum

“God Almighty has abundantly shown His grace through the iron ore that appears in many places and widely spread fields in Skien.”

This was written in a report from the king’s miner Hans Glaser to King Christian III in 1538, marking the beginning of 328 years of mining and ironworks activity in Gjerpen, at Fossum Ironworks. Over these years, a significant mining community developed at Fossum until its closure in 1867.

In the early years, the ironworks operations were leased under the king’s authority. Especially during the first century, the running of the ironworks was highly variable and difficult. In 1624, Johan Post and Herman Krefting started the Iron Company and began blast furnace operations at Fossum. The king’s warfare and people’s needs increased the demand for cannons and iron stoves. The site had various owners until the Løvenskiold family took over. Chancellor Herman Leopoldus was ennobled with the name Løvenskiold in 1739. Governor Severin Løvenskiold built the main manor house from 1811 to 1818. Today, the Fossum estate is part of our shared cultural heritage, which the Løvenskiold family has owned and managed for nearly 300 years, now in its 10th generation. The forest, the waterfall, and the iron-nature was a resource.

Norway’s oldest iron mine, the Glaser Mine, was staked and opened in 1538–39. After this, hundreds of mines and prospects in the Fossum forests were exploited using fire-setting. Several have disappeared due to housing development and backfilling, but traces and memories of mining activity remain. The Glaser Mine, with its adit and many shafts, is, for example, a popular hiking destination. The horse was an invaluable work tool, and the remains of horse paths are visible evidence of this. Traces of charcoal kilns and ore roads are other examples. It is estimated that in the 17th and 18th centuries, the home mines supplied about one-third of the ore needs, with the rest mainly coming from mines in Kragerø, Arendal, and Ulefoss.

What is iron ore?

Iron ore refers to a group of minerals in which the iron content is high enough to be extracted economically. The most common ores are magnetite and hematite. In the Fossum iron mines, the main ore extracted was magnetite, Fe₂O₄ (magnetic iron ore), recognizable by its black and shiny appearance. If you place a compass next to the iron ore, the needle will move. The iron ore deposits in the Fossum forests consist of veins mainly of magnetite and quartz. The veins are usually between 10 and 50 cm wide, but range from a few millimeters to several meters. The longest veins can be traced for 2–3 km through the terrain.