Cabin Branch Pyrite Mine Historic District is a national historic district located at Prince William Forest Park, Triangle, Prince William County, Virginia. It encompasses 4 contributing sites and 42 contributing structures associated with the Cabin Branch pyrite mine. The pyrite mine opened in 1889, and remained in operation until 1919 or 1920. The property includes a number of capped mine shafts, and the remains of a commissary building and an old mill; and mine structures, including crusher house, mill, mechanical and support buildings, numerous rail lines.[3]
