Mineral, Specifically An Iron Ore

Botryoidal Goethite

Goethite (α-Fe3+O(OH))

Limonite Pseudomorph after Pyrite

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

Limonite Concretion

Goethite-rich Concretion (FeO(OH))

Magnetite Ore

Magnetite (Fe3O4)

Dyed Blue Agate

Silicon dioxide (SiO2) with artificial pigment

Weathered iron-rich rock, likely limonite/goethite-bearing material

Limonite (hydrated iron oxides; commonly goethite, FeO(OH), with hematite and clay)

Hematite Ball

Iron(III) oxide (Fe2O3)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Limonite (Iron Ore)

Limonite (mixture of hydrated iron(III) oxide-hydroxides)

Fancy Jasper

Silicon Dioxide (SiO₂)

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Yellow Ochre (Limonite)

Limonite (FeO(OH)·nH2O)

Magnetite or Hematite Nodule

Iron Oxide (Fe3O4 or Fe2O3)

Limonite (Limonitic Sandstone)

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

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Fluorite

Calcium Fluoride (CaF2)

Hematite

Hematite (Fe2O3)

Blue metallic mineral specimen, possibly bornite or chalcopyrite

Bornite (Cu₅FeS₄) or chalcopyrite (CuFeS₂); exact identification requires testing

Likely polished dark metallic mineral specimen

Indeterminate from image; possibly hematite, magnetite, or galena

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Banded Iron Formation (Fragment)

Banded Iron Formation (BIF)

Botryoidal Hematite (Kidney Ore)

Iron(III) oxide (Fe2O3)

Limonite (Oxidized Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Tumbled chalcopyrite (likely)

Chalcopyrite, CuFeS₂

Citrine

Citrine (Silicon Dioxide, SiO2)

Rose Quartz

Silicon dioxide (SiO2)

Iron-rich metamorphic rock, likely hematite-bearing schist or ironstone

Hematite/goethite-rich quartz–mica schist or banded ironstone; Fe₂O₃ and FeO(OH) are probable major iron minerals

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Likely hematite-rich ironstone or metallic mineral fragment

Hematite (Fe₂O₃), possibly with magnetite (Fe₃O₄) or metallic iron

Limonite Geode (Ironstone Concretion)

Limonite [FeO(OH)·nH2O] with possible Quartz or Calcite interior

Bornite

Copper Iron Sulfide (Cu5FeS4)

Limonite Concretion

FeO(OH)qnH2O (Hydrated iron(III) oxide-hydroxide mixture)

Amethyst

SiO2 (Silicon Dioxide with iron impurities)

Limonite (Iron Ore)

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

Hematite

Iron(III) oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Milky Quartz with Iron Inclusion

Silicon Dioxide (SiO2)

Yellow Ochre / Limonite

Hydrated ferric oxide (FeO(OH)·nH2O)

Limonite Sandstone

Ferruginous Sandstone (Hydrated Iron Oxide)

Amethyst (Tumbled)

Amethyst (SiO2 with iron impurities)

Chert (Iron-stained)

Chert (Microcrystalline Quartz, SiO2)

Hematite

Hematite (Iron(III) oxide, Fe2O3)