Mineral (Iron Ore)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)

Limonite (Limonitic Sandstone)

Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)

Ironstone (iron-oxide-rich rock)

Ferruginous ironstone, likely limonite/goethite-rich; exact identification requires testing

Magnetite or Ironstone Nodule

Magnetite (Fe3O4) or Hematite-rich Sedimentary Nodule

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Botryoidal hematite (ironstone)

Hematite, α-Fe₂O₃, likely with goethite and iron-rich matrix

Possibly banded ironstone (iron-rich metamorphic rock)

Likely iron formation, composed chiefly of hematite or goethite with silica-rich layers; exact identification is uncertain from the photo

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Specular Hematite

Hematite (Fe2O3)

Limonite (Iron Ore)

Limonite (unstructured hydrated iron(III) oxide-hydroxides, often FeO(OH)·nH2O)

Hematite pseudomorph after a fossil or mineralized object (likely iron-oxide concretion)

Hematite, Fe₂O₃, possibly limonite/goethite-bearing

Likely magnetite-rich rock (lodestone)

Magnetite, Fe₃O₄, possibly in a fine-grained host rock

Hematite Nodules (Moqui Marbles or similar)

Iron oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Limonite (Iron Ore)

Hydrous Iron Oxide (goethite, lepidocrocite)

Pyrite-bearing sulfide specimen

Pyrite (FeS₂), possibly with chalcopyrite (CuFeS₂) and/or marcasite

Hematite

Hematite (Fe2O3)

Turquoise color-bead and Hematite necklace

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

Limonite (Iron Ore)

Limonite (mixed iron hydroxides, primarily FeO(OH)·nH2O)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Limonite (Iron Ore)

Limonite (Hydrous iron(III) oxide-hydroxide mixture, FeO(OH)·nH2O)

Limonite Concretion

Limonite (Hydrated iron(III) oxide-hydroxide) FeO(OH)·nH2O

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Hematite

Hematite (Fe2O3)

Magnetite-rich iron ore

Magnetite (Fe₃O₄), possibly massive magnetite/ironstone

Likely iron-rich rock or meteorite fragment

Indeterminate; possible hematite-/magnetite-bearing material

Rounded iron-rich pebble

Likely ironstone or ferruginous quartzite; exact identification requires testing

Polished blue-green metallic mineral specimen, likely bornite (“peacock ore”)

Bornite, Cu₅FeS₄; possibly chalcopyrite, CuFeS₂, with iridescent tarnish

Limonite (Ironstone Concretion)

Limonite (Hydrous ferric oxide mixture, FeO(OH)·nH2O)

Limonite Sandstone

Ferruginous Sandstone (Hydrated Iron Oxide)

Limonite (Iron Ore)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Botryoidal Goethite

Goethite (α-Fe3+O(OH))

Limonite Pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O replacing Pyrite FeS2

Brown botryoidal mineral specimen, likely goethite/limonite

Goethite (α-FeO(OH)), possibly mixed with limonite (hydrated iron oxides)

Iron-rich rock, possibly ironstone

Likely ferruginous sandstone or ironstone; exact identification requires testing

Banded ironstone (likely jasper-rich ironstone)

Iron-rich chert/jasper with iron oxides, chiefly hematite and goethite; exact identification requires testing

Polished hematite (possibly specular hematite)

Hematite, α‑Fe₂O₃

Hematite Nodular Concretion

Iron(III) oxide (Fe2O3)

Possible hematite-bearing pebble

Hematite, Fe₂O₃, possibly mixed with magnetite or iron-rich matrix

Iron-rich goethite/limonite specimen

Goethite, α-FeO(OH), commonly mixed with limonite and other iron oxides

Polished hematite

Hematite (Fe₂O₃), likely a tumbled specimen