CLAUSTHAL, or KLAUSTIIAL  , a town of Germany, in the Prussian Harz, lying on a bleak plateau, 186o ft. above sea-level, 50 . M. by rail W.S.W. of Halberstadt . Pop . (1905) 8565 . Clausthal is the chief mining town of the Upper Harz Mountains, and practically forms one town with Zellerfeld, which is separated from it by a small stream, the Zellbach . The streets are broad, opportunity for improvement having been given by fires in 1844 and 1854; the houses are mostly of wood . There are an Evangelical and a Roman Catholic church, and a gymnasium . Clausthal has a famous mining college with a mineralogical museum, and a disused mint . Its chief mines are silver and lead, but it also smelts copper and a little gold . Four or five sanatoria are in the neighbourhood . The museum of the Upper Harz is at Zellerfeld . Clausthal was founded about the middle of the 12th century in consequence probably of the erection of a Benedictine monastery (closed in 1431), remains of which still exist in Zellerfeld .

At the beginning of the 16th century the

dukes of Brunswick made a new settlement here, and under their directions the mining, which had been begun by the monks, was carried on more energetically . The first church was built at Clausthal in 1570 . In 1864 the control of the mines passed into the hands of the state .