Mineral (Iron Ore)

Ironstone Concretion / Limonite Node

Goethite and Limonite (FeO(OH) nH2O)

Magnetite / Hematite (Iron Ore Pebble)

Fe3O4 (Magnetite) / Fe2O3 (Hematite)

Weathered iron-rich rock or concretion

Likely limonite/goethite-bearing concretion; exact identification requires testing

Ironstone / limonite-rich concretion

Hydrated iron oxides, chiefly limonite/goethite (FeO(OH)·nH₂O), possibly with hematite

Limonite on Sandstone

Iron Oxyhydroxide (FeO(OH)·nH2O) on Quartz Sandstone

Magnetite

Magnetite (Fe3O4)

Turquoise and Hematite

Turquoise (CuAl6(PO4)4(OH)8·4H2O) and Hematite (Fe2O3)

Limonite Pseudomorph after Pyrite

Limonite (Hydrous iron oxides, FeO(OH)·nH2O) replacing Pyrite (FeS2)

Hematite

Iron(III) oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Pyrite in Matrix (often with Chalcopyrite)

Iron Sulfide (FeS2) / Copper Iron Sulfide (CuFeS2)

Gossan (with Limonite and Hematite)

Gossanous iron-oxide rock (Fe2O3 · nH2O)

Botryoidal Hematite (Iron Stone Conglomerate)

Hematite (Fe2O3) in sedimentary matrix

Iron-Oxide Concretion (Moqui Marble)

Goethite/Hematite Concretion (Fe2O3 / FeO(OH))

Pyrite with Galena and Sphalerite on Matrix

Iron Sulfide (FeS2), Lead Sulfide (PbS), Zinc Sulfide (ZnS)

Iron-rich concretion or weathered ironstone

Goethite–hematite limonite aggregate; commonly described as limonite or ironstone

Hematite Nodular Iron Ore

Hematite (Fe2O3)

Copper Ore (with Malachite/Chrysocolla and Iron Oxides)

Secondary Copper Minerals (Cu2(CO3)(OH)2 / (Cu,Al)2H2Si2O5(OH)4·nH2O)

Ironstone Nodules (Iron Concretion)

Siderite or Hematite Concretion

Limonite (Iron Stone/Ocher)

Limonite (FeO(OH)·nH2O)

Limonite Concretion

FeO(OH)·nH2O (Hydrated Iron Oxide)

Hematite

Iron(III) oxide (Fe2O3)

Magnetite / Hematite (Iron Ore)

Magnetite (Fe3O4) or Hematite (Fe2O3)

Limonite / Ironstone Nodule

Hydrated Iron Oxide (FeO(OH)·nH2O)

Specular Hematite (Iron Ore)

Hematite (Alpha-Fe2O3)

Specular Hematite with Pyrite

Iron Oxide (Fe2O3) with Iron Sulfide (FeS2)

Goethite

Goethite (FeO(OH))

Banded Iron Formation (BIF)

Banded Iron Formation

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Peacock Ore

Bornite (Cu5FeS4)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Chrysocolla (with Hematite/Iron Oxides)

Chrysocolla: (Cu, Al)2H2Si2O5(OH)4 · nH2O

Pyrite

Iron Sulfide (FeS2)

Gossan (Iron Hat)

Gossan (secondary iron oxide cap)

Limonite and Goethite encrusted Chert/Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O) with cryptocrystalline Silica (SiO2)

Banded Iron Formation

Banded Iron Formation (BIF)

Lake Superior Agate

Chalcedony (SiO2 with iron impurities)

Hematite

Iron(III) oxide (Fe2O3)

Iron Concretion

Ferruginous concretion (Fe2O3·nH2O / FeO(OH))

Hematite

Hematite (Fe2O3)