Iron ore (fines)
The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite (Fe 3 O 4 ), hematite (Fe 2 O 3 ), goethite (FeO (OH)), limonite (FeO (OH).n (H 2 O)) or siderite (FeCO 3 ).