Kongsberg Silver Mines
The silver mines of Kongsberg, in Buskerud county in Norway, constitute the largest mining field in Norway, with over 80 different mines. It was the largest pre-industrial working place in Norway, with over 4,000 workers at its peak in the 1770s and supplied over 10% of the gross national product of the Danish–Norwegian union during its 335-year-long history: over 450,000 man-years were expended in the production.
Sulitjelma Mines
Several technical innovations and inventions were made at Sulitjelma, including the Knudsen process and some of the world's first electric copper smelters. Later in the history of the works many other improvements were made, especially in concentrating ore and smelting. In the early 1900s, Sulitjelma Mines was the second-largest industrial company in Norway.