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.
Oil shale industry
The largest oil shale mine in the world is the Estonia Mine, operated by Enefit Kaevandused. In 2005, Estonia mined 14.8 million tonnes of oil shale. During the same period, mining permits were issued for almost 24 million tonnes, with applications being received for mining an additional 26 million tonnes. In 2008, the Estonian Parliament approved the "National Development Plan for the Use of Oil Shale 2008-2015", which limits the annual extraction of oil shale to 20 million tonnes.