Mineral (Iron Ore)

Iron-rich hematite/goethite concretion (likely limonite)

Hematite (Fe₂O₃) with goethite (FeO(OH)) and limonite

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Ironstone Nodules (Iron Concretion)

Siderite or Hematite Concretion

Weathered iron-rich rock or concretion

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

Iron Slag

Ferrous Slag (Silicate/Oxide mixture)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Iron-Oxide Concretion (Moqui Marble)

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

Hematite

Iron(III) oxide (Fe2O3)

Likely weathered iron-rich rock or laterite

Uncertain; possible limonite/goethite-rich laterite (FeO(OH)·nH₂O)

Magnetite

Magnetite (Fe3O4)

Botryoidal hematite/goethite specimen

Hematite (Fe₂O₃), likely with goethite (FeO(OH)) and minor limonite

Pyrite

Iron Sulfide (FeS2)

Banded Iron Formation (BIF)

Banded Iron Formation (principally Hematite/Magnetite and Chert)

Iron-rich breccia or weathered ironstone

Goethite–hematite-bearing ferruginous rock, possibly limonite

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich ironstone; commonly approximated as hydrated iron oxides (FeO(OH)·nH₂O)

Limonite / Ironstone Nodule

Hydrated Iron Oxide (FeO(OH)·nH2O)

Weathered iron-rich rock, likely limonite/goethite-bearing sandstone or laterite

Hydrated iron oxides, chiefly limonite (FeO(OH)·nH₂O) and goethite (α-FeO(OH)), possibly cementing sandstone

Botryoidal hematite (specular hematite)

Hematite, Fe₂O₃

Magnetite (Lodestone variant potential)

Magnetite (Fe3O4)

Unidentified dark metallic sulfide specimen

Possibly pyrite-, chalcopyrite-, or galena-bearing ore; exact identification requires testing

Limonite (Iron Stone Concretion)

Limonite (Hydrous Iron Oxide) - FeO(OH)·nH2O

Limonite (Iron Stone)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

Likely lateritic ironstone (limonite/goethite-rich)

Goethite, α-FeO(OH), with possible limonite and clay impurities

Ironstone Pebble

Sedimentary Ironstone (Hematite/Limonite-bearing)

Limonite and Goethite

Limonite (hydrated iron(III) oxide-hydroxide) and Goethite (α-FeO(OH))

Ironstone / limonite-rich concretion

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

Magnetic Hematite (Man-made)

Iron Oxide (Fe2O3) with Barium-Strontium Ferrite

Magnetite-rich iron ore

Magnetite (Fe₃O₄), possibly with hematite and silicate matrix

Weathered iron-rich stone, possibly limonite-bearing rock

Limonite/goethite-rich material; composition commonly approximated as hydrated iron oxides, FeO(OH)·nH₂O

Magnetite

Iron(II,III) oxide (Fe3O4)

Likely specular hematite

Hematite (Fe₂O₃), probably a micaceous/specular variety

Hematite Concretion

Iron(III) oxide (Fe2O3)

Hematite

Hematite, Iron(III) oxide (Fe2O3)

Specular Hematite (Polished Sphere)

Hematite (Alpha Fe2O3)

Iron-rich breccia or ironstone

Hematite/goethite-bearing breccia; likely Fe₂O₃–FeO(OH) with silica and iron-stained rock fragments

Weathered iron-rich concretion

Goethite–hematite limonite concretion, likely with quartz and clay minerals

Weathered iron-rich stone, possibly limonite-bearing sandstone or laterite

Limonite/goethite-rich material; composition commonly FeO(OH)·nH₂O with clay and quartz impurities

Pyrite in Quartzite/Graphite Matrix

Iron Sulfide (FeS2)

Polished hematite

Hematite (Fe₂O₃), likely a tumbled iron-oxide specimen

Weathered iron-rich concretion or limonite/goethite nodule

Limonite (largely hydrated iron oxides; commonly goethite, FeO(OH), and hematite, Fe₂O₃)

Magnetite (Charnockite Regional Variation)

Magnetite (Fe3O4)

Hematite

Iron oxide (Fe2O3)