In the eastern part of the Strzelinski Hills, between the places of Strzelin and Ziebice, within the Sudeckiego Foreland, quartzite quarry "Jeglowa" is located. Quartzite slate mining began here in the late XIX century. Nowadays it is one of the few in the world and the only one of the kind in Poland deposit which contains high quality natural refractory material. The visitors are greatly attracted by the rock crystals that can be found together with smaller deposits of kaolin.