Mineral (Iron Ore)

Hematite (Polished / Tumbled)

Iron Oxide (Fe2O3)

Limonite (often after Hematite or Goethite)

Limonite (FeO(OH)·nH2O)

Metallic sulfide ore specimen

Likely pyrite-bearing massive sulfide, possibly pyrrhotite or galena; exact identification requires testing

Gold-bearing dark rock, possibly magnetite with iron-oxide staining

Likely magnetite (Fe₃O₄) with limonite/goethite; metallic patches may be gold or weathered sulfide, unconfirmed

Pyrite (Limonite Pseudo-morph after Pyrite)

Iron sulfide (FeS2) transitioning to Iron oxide-hydroxide (FeO(OH)·nH2O)

Unidentified weathered mineral/rock fragment

Indeterminate; likely a weathered iron-rich silicate or sulfide-bearing specimen

Iron-rich weathered stone, possibly limonite/goethite

Limonite (mixture of hydrated iron oxides), commonly goethite (α-FeO(OH))

Pyrite (fool’s gold)

Pyrite, iron disulfide (FeS₂)

Tumbled Hematite

Hematite (Alpha iron oxide, Fe2O3)

Hematite bead bracelet

Hematite (Fe₂O₃), likely polished or magnetically enhanced beads

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Limonite/Goethite Nodule

Iron Oxyhydroxide (primarily FeO(OH)·nH2O)

Hematite (Concretion)

Iron(III) oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Iron Concretion

Ferruginous concretion (Fe2O3·nH2O / FeO(OH))

Iron-rich rock, possibly limonite/goethite

Hydrated iron oxides/hydroxides, commonly limonite (FeO(OH)·nH₂O) with goethite (α-FeO(OH))

Weathered banded iron formation (iron-rich quartzite)

Banded iron formation (BIF), chiefly hematite/magnetite and microcrystalline quartz (SiO₂)

Hematite Nodule

Hematite (Fe2O3)

Magnetite (likely in Hematite or Ironstone)

Magnetite (Fe3O4)

Iron-rich weathered rock or limonite/goethite nodule

Limonite (mixture dominated by goethite, FeO(OH)·nH₂O), possibly with quartz or clay

Yellow Ochre / Limonite

FeO(OH)·nH2O (Hydrated Iron Oxide Mix)

Botryoidal hematite (ironstone)

Hematite, Fe₂O₃; likely a botryoidal or massive iron-oxide specimen

Likely weathered metallic mineral or slag fragment

Indeterminate; possibly iron-rich sulfide/oxide material or industrial slag

Iron-rich rock, likely hematite/goethite-rich ironstone

Hematite (α-Fe₂O₃), possibly mixed with goethite (FeO(OH)) and gangue minerals

Banded Iron Formation

BIF (Banded Iron Formation)

Weathered iron-rich pebble

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

Hematite bead bracelet

Hematite (iron(III) oxide, Fe₂O₃), likely polished specular hematite

Hematite

Iron(III) oxide (Fe2O3)

Lake Superior Agate

Cryptocrystalline Quartz (SiO2 with Iron impurities)

Magnetite (potentially Lodestone)

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

Galena-bearing sulfide specimen

Galena (PbS), possibly with sphalerite and iron sulfides

Uncertain dark-and-white rock fragment

Likely a mixed lithic specimen, possibly quartz-bearing granite or ore; exact identification is not possible from the photograph

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Possible iron-rich concretion or weathered ironstone

Goethite/limonite-rich ironstone; exact identification requires testing

Ferruginous Sandstone

Arenite with Iron-Oxide cement (Fe2O3 · nH2O)

Polished magnetite-rich stone (probable magnetite or hematite)

Magnetite, Fe₃O₄; possibly hematite, Fe₂O₃

Small dark mineral specimen, possibly hematite or magnetite

Indeterminate from the image; possible hematite (Fe₂O₃) or magnetite (Fe₃O₄)

Gossan (Limonite/Ironstone)

Hydrated Iron Oxide (FeO(OH)·nH2O)

Botryoidal Goethite on Quartz

Goethite (α-Fe3+O(OH)) on Quartz (SiO2)

Tumbled dark stone, possibly hematite

Hematite (Fe₂O₃), provisional identification

Limonite Concretion

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

Limonite (Gozzany Iron)

Limonite (FeO(OH)·nH2O)