Mineral (Iron Ore)

Concretion

Sedimentary Concretion (e.g., Siderite or Ironstone)

Polished black stone, likely hematite

Hematite (Fe₂O₃), possibly magnetite or a hematite-rich ironstone

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Likely limonite/goethite-rich ironstone

Limonite (amorphous hydrated iron oxides), commonly mixed with goethite, hematite, and host rock

Banded Iron Formation

Banded Iron Formation (BIF)

Limonite with Quartz

FeO(OH)·nH2O (Limonite) with SiO2 (Quartz)

Likely hematite-rich iron ore or magnetite-bearing stone

Hematite (Fe₂O₃), possibly mixed with magnetite (Fe₃O₄) and silicate gangue

Magnetite (Iron Ore)

Iron(II,III) oxide (Fe3O4)

Hematite (Nodular or Botryoidal)

Iron(III) oxide (Fe2O3)

Slag

Metallurgical Slag

Likely magnetite-rich iron ore

Magnetite (Fe₃O₄), possibly in a dense massive ironstone matrix

Iron-oxide-rich limonite/goethite ore

Limonite (principally goethite, α-FeO(OH), with hydrated iron oxides); possible manganese oxides

Magnetite / Iron Ore

Magnetite (Fe3O4)

Hematite

Hematite (Fe2O3)

Black Sand (Magnetite Sand)

Magnetite (Fe3O4)

Iron-rich concretion or weathered ironstone

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

Native Copper with Malachite/Oxide Coating

Native Copper (Cu)

Banded Iron Formation (BIF)

Banded Iron Formation

Magnetite

Iron(II,III) oxide (Fe3O4)

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

Hydrated iron oxides/hydroxides, chiefly limonite-goethite mixture; exact identification requires testing

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Sandstone Concretion

Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Small red-brown mineral or rock fragment

Unidentified; possibly iron-oxide-rich jasper, garnet, or weathered sulfide

Hematite / Goethite (Iron Ore)

Iron Oxide (Fe2O3 / FeO(OH))

Ironstone Concretion (Siderite Nodules)

Siderite (FeCO3) in Mudstone or Sandstone matrix

Chalcedony on Ironstone

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3/FeOOH)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Gossanous Sandstone (likely Terrestrial)

Arenite with Iron-Oxide inclusions

Botryoidal hematite–goethite specimen (probable)

Hematite (Fe₂O₃) with goethite (FeO(OH)), possibly limonite

Chrysocolla (with Hematite/Iron Oxides)

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

Likely ironstone or weathered iron-rich rock

Hematite/goethite-bearing ferruginous concretion; exact identification requires testing

Ironstone Concretion (Pot Stone)

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Weathered iron-rich sedimentary rock (probable laterite/ironstone)

Limonite/goethite-rich ferruginous material; commonly approximated as FeO(OH)·nH₂O with clay and quartz

Iron-rich breccia (hematite–goethite rock)

Hematite (Fe₂O₃) and goethite (FeO(OH)) ironstone, likely ferruginous breccia

Banded iron formation fragment (ironstone)

Banded iron formation; chiefly hematite/magnetite with chert (SiO₂)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Milky Quartz with Iron Oxide

Quartz (Silicon Dioxide, SiO2) with Limonite/Goethite staining

Hematite

Iron Oxide (Fe2O3)

Weathered iron-rich rock fragment

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

Ironstone (iron-oxide-rich rock)

Likely goethite/limonite-rich ironstone; exact identification requires closer examination

Hematite

Iron(III) oxide (Fe2O3)