Publication Summary

Holden Mine on Railroad Creek in the Washington Cascades shut down in 1957. As part of Holden Mine's legacy to the area, several tailing piles were left on the surrounding landscape. The associated environmental impact on Railroad Creek from the acid mine drainage and seepage from the tailing piles can be visually observed in the creek bed. Mine drainage and seeps from the tailing piles are known inputs to the creek of acid wastes and metals. The impact of the tailing pile material on the creek is not as well known.

This study examines the stream sediments to determine if the tailing pile material is still entering the creek. Size and density separation of the sediments followed by microscopical examination of the particulate matter showed the presence of tailing pile particulate matter in the stream sediments. The mine tailing grains are recognizable microscopically by the presense of an orange-yellow "goethite" coating on the mineral grains. Microchemical testing for solubility of the coating in warm hydrochloric acid and heating in a closed capillary help distinguish the coated grains from the naturally yellow-colored grains in the sediments. Particulate matter characteristic of the mine tailings was found in all three sediment samples collected below the tailing piles.