Mineral, Specifically An Iron Ore

Iron-rich rock, likely limonite/goethite-stained ore

Goethite (α-FeO(OH)) and/or limonite, a mixture of hydrated iron oxides

Moss Agate

Chalcedony (SiO2 with inclusions)

Amethyst (Tumbled)

Amethyst (SiO2 with iron impurities)

Banded Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Dyed Blue Agate

Silicon dioxide (SiO2) with artificial pigment

Copper-bearing sulfide ore, likely chalcopyrite with iron oxides

Chalcopyrite (CuFeS₂), possibly associated with bornite (Cu₅FeS₄), pyrite, and limonite/goethite

Pink Granite

Granite (Alkali-feldspar granite)

Ironstone / limonite-rich concretion

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

Banded Iron Formation

Banded Iron Formation (BIF)

Iron-rich botryoidal limonite/goethite specimen

Limonite (amorphous hydrated iron oxides, chiefly goethite, α-FeO(OH))

Tumbled magnetite (likely)

Magnetite, Fe₃O₄

Limonite (Iron Ore)

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

Yellow Jasper

SiO2 (Silicon Dioxide)

Limonite (with goethite)

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

Limonite (Iron Ore)

Hydrated ferric oxide mixture (FeO(OH)·nH2O)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Limonite Concretion

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)wnH2O)

Raw botryoidal goethite/limonite specimen

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

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Iron-rich quartz specimen (likely hematite/goethite-coated quartz)

Quartz (SiO₂) with iron oxides, chiefly hematite (Fe₂O₃) and/or goethite (FeO(OH)); precise identification requires testing

Botryoidal hematite (ironstone)

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

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

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

Amethyst

SiO2 (Silicon Dioxide with iron impurities)

Pyrite-bearing sulfide ore

Pyrite (FeS₂), possibly mixed with chalcopyrite and/or other sulfides

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Limonite/Ironstone

Limonite (Hydrous ferric oxides), FeO(OH)·nH2O

Iron-rich breccia or hematite-bearing ironstone

Hematite–goethite ironstone, possibly brecciated jasper; chiefly Fe₂O₃ and FeO(OH)

Hematite Pebble

Hematite (Fe2O3)

Limonite / Ironstone

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

Iron-rich rock or Concretion

Ironstone or Limonite concretion

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich iron oxide (hydrated FeO(OH)·nH₂O), possibly with hematite

Hematite

Hematite (Fe2O3)

Limonite (Iron Ore)

FeO(OH)·nH2O

Botryoidal Hematite

Iron(III) oxide (Fe2O3)

Ferruginous Quartz

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Small metallic mineral fragment

Indeterminate; possibly galena, hematite, magnetite, or metallic meteorite fragment

Weathered iron-rich rock, possibly limonite-bearing quartzite or ironstone

Goethite–hematite/limonite with quartz; exact identification requires testing

Citrine

Citrine (Silicon Dioxide, SiO2)

Hematite

Iron(III) oxide (Fe2O3)

Chert (Jasper variety)

Chert (SiO2)

Rose Quartz

Silicon dioxide (SiO2)

Polished hematite pebble

Hematite, Fe₂O₃