Mineral (Iron Ore)

Magnetite Sand (Black Sand)

Magnetite (Fe3O4)

Bauxite / Iron-rich Laterite

Laterite (principally Al(OH)3, Fe2O3, and SiO2)

Pyrite

Iron Sulfide (FeS2)

Ferruginous Sandstone (Ironstone)

Sedimentary rock with high iron oxide content (Fe2O3 / FeO(OH))

Epidosite

Epidosite (predominantly Epidote {Ca2Al2Fe3+Si3O12(OH)} and Quartz {SiO2})

Slag (Industrial)

N/A (Anthropogenic Slag)

Ironstone Nodule (Ironstone Concretion)

Siderite-rich Mudstone (FeCO3) or Limonite (FeO(OH)·nH2O)

Magnetite (Lodestone)

Magnetite (Fe3O4)

Ironstone Concretion

Siderite or Limonite Concretion

Magnetite

Magnetite (Fe3O4)

Pyrite

Iron Sulfide (FeS2)

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Ferruginous Sandstone

Arenite with Iron-Oxide cement (primarily Fe2O3 • nH2O)

Greenschist

Chlorite schist

Banded Iron Formation (BIF)

Banded Iron Formation

Banded Iron Formation (BIF) / Tiger Iron

Banded Iron Formation containing Hematite (Fe2O3) and Magnetite (Fe3O4)

Beryl (Aquamarine) in Matrix

Beryllium aluminum silicate (Be3Al2(SiO3)6)

Quartz with Pyrite

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2)

Magnetite

Magnetite (Iron(II,III) oxide, Fe3O4)

Banded Iron Formation (BIF) / Tiger Iron

Ferruginous Chert (primarily Quartz [SiO2] and Hematite/Magnetite [Fe2O3/Fe3O4])

Ferruginous Conglomerate

Conglomerate with Iron-Oxide Matrix (SiO2 + Fe2O3/FeO(OH))

Limonite stained Sandstone

Sedimentary rock with Goethite/Limonite (FeO(OH)·nH2O)

Banded Iron Formation (BIF) / Tiger Iron variety

Banded Iron Formation (composed primarily of Magnetite Fe3O4, Hematite Fe2O3, and Chert/Quartz SiO2)

Ironstone Concretion (Moqui Marble)

Iron-oxide Concretion (Hydrated ferric oxide, Fe2O3·nH2O)

Pyrite

Iron Sulfide (FeS2)

Ferruginous Sandstone (Ironstone Nodules)

Ferruginous Sandstone with Limonite/Goethite coating (Fe2O3·H2O)

Pyrite

Iron Sulfide (FeS2)

Banded Iron Formation (BIF) with Quartz

Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)

Ironstone Concretion (Limonite/Goethite)

Ferruginous Sandstone / Ironstone (FeO(OH)·nH2O)

Bauxite

AlOx(OH)3-2x (mixture of Gibbsite, Boehmite, and Diaspore)

Bornite

Bornite (Cu5FeS4)

Bauxite

Al2O3·2H2O (principally composed of gibbsite, boehmite, and diaspore)

Ferruginous Sandstone (Ironstone Conglomerate fragments)

Ferruginous clastic sedimentary rock (SiO2 cemented by Fe2O3)

Banded Iron Formation (BIF)

Banded Iron Formation (composed primarily of Hematite [Fe2O3], Magnetite [Fe3O4], and Chert [SiO2])

Ferruginous Sandstone

Arenite with Hematite/Limonite cement (SiO2 + Fe2O3)

Banded Iron Formation (BIF)

Banded Iron Formation (predominantly Hematite, Magnetite, and Chert/Quartz)

Banded Iron Formation (Red Jasper and Hematite Chert)

Banded Iron Formation (BIF); Fe2O3 (Hematite) + SiO2 (Quartz/Jasper)

Milky Quartz with Mineral Inclusions

Quartz (Silicon Dioxide, SiO2)

Laterite

Laterite (no specific mineral formula as it's a rock type)

Chalcopyrite-bearing Ore

Chalcopyrite (CuFeS2)

Ferrocoke or Slag

Anthropogenic pyrometallurgical residue

Ferruginous Sandstone (Ironstone)

Sandstone with Hematite/Goethite cement (SiO2 + FeO(OH))