Mineral (Processed Metal)

Turquoise and Hematite

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

Sandstone

Arenite (SiO2 principal)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hematite (Oolitic or Earthy variety)

Iron(III) oxide (Fe2O3)

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Pyrite Geode

Iron Disulfide (FeS2)

Silver (Native Element)

Silver (Ag) in an alloy of 90% Silver and 10% Copper

Pyrite (Fool's Gold) Ore

Iron Disulfide (FeS2)

Gold

Native Gold (Au)

Gold Nugget

Native Gold (Au)

Specular Hematite (Iron Ore)

Iron(III) oxide (Fe2O3)

Gold Nugget

Native Gold (Au)

Turquoise and Hematite

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

Gold in Matrix

Native Gold (Au)

Cupronickel (on a 1981 Mexico 20 Pesos coin)

Copper-Nickel Alloy (Cu75Ni25)

Iron Ore (Limonite and Hematite)

Goethite/Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Sunstone

Oligoclase (Plagioclase Feldspar), (Na,Ca)(Si,Al)4O8

Fluorite

Calcium Fluoride (CaF2)

Bauxite

Bauxite (Mixture of Al(OH)3, AlO(OH), and Fe2O3)

Limonite

Limonite (Hydrous iron oxides, predominantly Goethite FeO(OH)·nH2O)

Gold

Native Gold (Au)

Pyrite

Iron Disulfide (FeS2)

Sunstone

Plagioclase feldspar (with Copper or Hematite inclusions)

Moonstone with Black Tourmaline

Orthoclase (KAlSi3O8) with Schorl inclusions (NaFe3Al6(BO3)3Si6O18(OH)4)

Specular Hematite with Quartz and Limonite

Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)

Specular Hematite (Polished Sphere)

Hematite (Alpha Fe2O3)

Native Gold

Gold (Au)

Note: Image shows a biological specimen (Rat), not a rock. Representative geological equivalent: Galena (due to lead-grey colors in fur).

Galena (PbS)

Limonite (Iron Ore)

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

Hypersthene

Hypersthene ((Mg,Fe)SiO3)

Peacock Ore (Bornite/Chalcopyrite)

Bornite (Cu5FeS4) or Chalcopyrite (CuFeS2)

Pyrite in Matrix (often with Chalcopyrite)

Iron Sulfide (FeS2) / Copper Iron Sulfide (CuFeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Native Gold Nugget

Native Gold (Au)

Red Hematite

Iron(III) oxide (Fe2O3)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Chromium (Chrome)

Chromium (Cr)

Pyrite and Sunstone

Iron Sulfide (FeS2) and Plagioclase Feldspar ((Ca,Na)Al(Al,Si)Si2O8)

Arsenopyrite

Arsenopyrite (FeAsS)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)