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.
Energy in Norway
In 2011, Norway was the eighth largest crude oil exporter in the world (at 78Mt), and the 9th largest exporter of refined oil (at 86Mt). It was also the world's third largest natural gas exporter (at 99bcm), having significant gas reserves in the North Sea. Norway also possesses some of the world's largest potentially exploitable coal reserves (located under the Norwegian continental shelf) on earth.