Dannemora, a parish of Sweden, in the Ian and about 23 m. N. of the city of Upsal; pop. about 1,000. It contains celebrated iron mines, which are situated in a marshy plain surrounded by three inland lakes. The principal mine is about 9,000 ft. long, 2,000 ft. broad, and 500 ft. deep. There are about 80 mines, which are protected against flooding from the lakes by a dam of hewn granite, rising in some places to a height of nearly 40 ft. The ore is obtained by blasting, and yields on an average 40 per cent, of pure iron. The annual production is estimated at upward of 30,000 tons. It is extensively used for making steel, being regarded as the best of its kind. About a mile from Dannemora are the forges of Osterby, where the ore is smelted by charcoal, and the iron prepared for exportation. Among the neighboring mining places, which are generally designated by the common name of the Dannemora works, are Lofsta, Gimo, Forsmark, Carl-holm, Stromsberg, and Ullfors.
Dannemora, a town of Clinton co., N. Y., 150 m. N. of Albany, formed from Beekman-town in 1854; pop. in 1870, 1,512. It is the seat of Clinton state prison, which in 1871 contained 529 convicts, mostly employed in the neighboring iron works and mines.