Mineral (Iron Ore)

Tumbled Hematite with Quartz/Chert (Specular Hematite)

Fe2O3 (Iron Oxide)

Limonitic ironstone / weathered iron-rich rock

Goethite–limonite aggregate; principally FeO(OH)·nH₂O with possible hematite (Fe₂O₃)

Iron-rich weathered rock, possibly ironstone

Ironstone (composition uncertain; likely iron oxides such as goethite and limonite)

Banded Iron Formation

Banded Iron Formation (BIF)

Magnetite / Iron Ore (likely Hematite-Magnetite mix)

Magnetite (Fe3O4)

Magnetite

Magnetite (Fe3O4)

Magnetite Nodule

Magnetite (Fe3O4)

Magnetite

Magnetite (Fe3O4)

Weathered iron-rich rock fragment

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

Polished black stone, likely hematite

Hematite (iron(III) oxide, Fe₂O₃), possibly black obsidian or another polished iron-rich mineral

Iron-rich weathered rock (likely limonite/goethite concretion)

Limonite–goethite mixture; chiefly FeO(OH)·nH₂O

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Likely ironstone concretion

Iron-oxide-cemented sedimentary concretion, commonly hematite/goethite-rich

Black Sand (Magnetite Sand)

Magnetite-rich Placers (Fe3O4)

Weathered iron-rich rock fragment

Likely limonite/goethite-rich ironstone; exact identification requires testing

Weathered iron-rich rock, possibly laterite or limonite-bearing quartzite

Limonite/goethite mixture, commonly FeO(OH)·nH₂O, with possible quartz and iron oxides

Limonite Concretion

Goethite/Limonite (FeO(OH)·nH2O)

Ironstone (Limonitic Concretion)

Limonite (FeO(OH)·nH2O) with Goethite and Hematite inclusions

Vesicular iron-rich slag or weathered metallic ore

Indeterminate; likely Fe-oxide-bearing slag (magnetite/hematite) rather than a specific natural mineral

Iron-rich sandstone or ferruginous rock

Ferruginous sandstone (quartz grains cemented by iron oxides, chiefly hematite and goethite)

Banded Iron Formation (BIF) / Tiger Iron variety

Banded Iron Formation (predominantly Hematite, Magnetite, and Chert/Quartz - SiO2 + Fe2O3)

Botryoidal hematite/goethite specimen

Hematite (Fe₂O₃), likely mixed with goethite (FeO(OH))

Pyrite

Iron Sulfide (FeS2)

Iron Ore (Goethite and Hematite)

Iron Oxyhydroxide (α-FeO(OH)) and Iron(III) oxide (Fe2O3)

Iron-rich concretion or slag-like mineral fragment

Likely limonite/goethite (FeO(OH)·nH₂O), possibly magnetite-bearing material

Ironstone Concretion

Siderite or Hematite Concretion

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) in Altered Host Rock

Ironstone with Limonite/Goethite coating

Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O)

Iron-stained quartz-rich rock

Likely quartz with iron-oxide staining (SiO₂ with goethite/limonite); exact identification is uncertain from the photo

Limitation Concretion

Ironstone Concretion (Goethite/Limonite)

Specularite (Specular Hematite)

Iron Oxide (Fe2O3)

Magnetite-rich Basalt

Basalt containing Fe3O4

Quartz with Chalcopyrite

Silicon Dioxide (SiO2) with Copper Iron Sulfide (CuFeS2)

Ironstone / Limonite Concretion

Hydrated Iron Oxide Rock (FeO(OH)·nH2O with SiO2)

Bauxite

Bauxite (Al(OH)3, AlO(OH))

Limonite/goethite-rich ironstone (probable)

Limonite, chiefly hydrated iron oxides; commonly goethite, α-FeO(OH), with possible quartz or host-rock inclusions

Earthy Hematite (Iron Ore)

Iron(III) oxide (Fe2O3)

Banded Iron Formation

Banded Iron Formation (BIF)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Specular Hematite

Hematite (Iron Oxide, Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Limonite (with Goethite/Ironstone)

FeO(OH)·nH2O (Hydrated Iron Oxide)