http://minerals.usgs.gov/minerals/pubs/commodity/iron_ore "U.S. Geological Survey" Iron ore « USGS Minerals Information: Iron Ore » « USGS Minerals Information: Iron Ore » https://minerals.usgs.gov/minerals/pubs/commodity/iron_ore/ Iron Ore US Geological Survey « USGS Minerals Information: Iron Ore » U.S. Geological Survey Catalog of minerals including iron ore https://minerals.usgs.gov/minerals/pubs/commodity/iron_ore/ Iron ore Iron ore