Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Limonite (Iron Ore/Bog Iron)

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

Quartz Pebble (Chalcedony/Agate variety)

Silicon Dioxide (SiO2)

Gold Nugget

Native Gold (Au)

Sandstone (Weathered Cobble)

Clastic Sedimentary Rock (primarily SiO2)

Limonite

Hydrous Iron Oxide (often Goethite FeO(OH), Lepidocrocite γ-FeO(OH), and other amorphous iron oxyhydroxides)

Limonite with Quartz (Gossan)

Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)

Chrysocolla on Quartz with Iron Oxides

Cu2-xAlx(H2-xSi2O5)(OH)4·n(H2O)

Agate (Chert/Chalcedony)

Silicon Dioxide (SiO2)

Agate (Geode nodule fragment)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Sapphire (Corundum)

Corundum (Al2O3)

Basalt (Stream-worn Cobble)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Cuprite

Cuprite (Copper(I) oxide, Cu2O)

Chrysocolla and Azurite on Matrix

Hydrated copper silicate (Cu,Al)2H2Si2O5(OH)4 (Chrysocolla) and Copper carbonate hydroxide Cu3(CO3)2(OH)2 (Azurite)

Quartz Pebble (Iron-stained)

Silicon Dioxide (SiO2)

Goethite (likely as part of Limonite/Ironstone)

Goethite (α-FeOOH)

Sandstone with Liesegang Rings

Arenite with Iron Oxide Concretions

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Rhodochrosite

Manganese Carbonate (MnCO3)

Chert (Arrowhead Preform or Flake)

Microcrystalline Quartz (SiO2)

Chert (specifically Gray/Black Chert)

Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminum phosphate)

Rough Emerald (Beryl)

Emerald (Be3Al2(SiO3)6 with Cr/V impurities)

Sandstone with Concretions / Liesegang Rings

Arenite with iron oxide banding

Foliated Gneiss (River-Worn Pebble)

Gneiss (High-grade Regional Metamorphic Rock)

Chrysocolla and Malachite Beads

Hydrated copper silicates (Chrysocolla) and Copper carbonate hydroxide (Malachite)

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Chert / Flint

Chert (SiO2)

Agate Geode

Cryptocrystalline Quartz (SiO2)

Limonite (after Pyrite Pseudomorph)

Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)

Agate (Common Chalcedony)

Silicon Dioxide (SiO2)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide inclusions (Hematite/Limonite)

Chert (variations include Flint or Jasper)

Silicon Dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline quartz (SiO2)

Bauxite (Laterite Clay)

Bauxite (mixture of Hydrous Aluminum Oxides: Gibbsite Al(OH)3, Boehmite and Diaspore AlO(OH))

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3)

Turquoise

Turquoise (CuAl6(PO4)4(OH)8·4H2O)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Limonite-stained Chert/Jasper

Microcrystalline Quartz (SiO2) with Iron Oxides (FeO(OH)·nH2O)

Gneiss (specifically a weathered or stream-worn specimen)

Gneiss (Foliated Metamorphic Rock)

Hemimorphite on Limonite Gossan

Hemimorphite (Zn4Si2O7(OH)2·H2O) on Limonite matrix

Chalcedony in Limestone Host Rock

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Hematite

Iron(III) oxide (Fe2O3)