Mineralogy and environmental geochemistry of historical iron slag, Hopewell Furnace National Historic Site, Pennsylvania, USA

► Historical iron slag is chemically dominated by Al2O3, Cao, MgO, and SiO2. ► Some samples are enriched in elements such as As, Cd, Cu, and Mn. ► Mineralogy is pyroxene, olivine, iron metal, glass; some melilite, spinel, sulfides. ► Al, Cu, Fe, and Mn leached during simulated weathering. ► Partitioning of elements among phases affects their potential release to environment.