The Frohnauer Hammer is an historic hammer mill in Frohnau, a village in the municipality of Annaberg-Buchholz in the Ore Mountains of southeast Germany. The mill is an important witness to proto-industrial development in the Ore Mountains. Of the once-numerous hammer mills only three others remain working in Saxony: the Dorfchemnitz Iron Hammer Mill, the Grünthal Copper Hammer Mill and the Freibergsdorf Hammer Mill.