Sedimentary Rock (Metamorphosed)

Sandstone

Arenite (SiO2-rich)

Sandstone

Arenite (composed primarily of SiO2)

Milky Quartz

Quartz (Silica / Silicon Dioxide), SiO2

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

River Stone (likely Siltstone or fine-grained Sandstone)

Clastic Sedimentary Rock (Lithic Wacke / Siltstone)

Sandstone

Arenite

Ferruginous Sandstone (Gozzan/Ironstone)

Arenite with Limonite/Goethite cement (FeO(OH)·nH2O)

Shale with Iron Oxide Staining

Fissile Mudstone (primarily clay minerals and quartz)

Green Jasper

Silicon Dioxide (SiO2) with impurities

Dalmatian Stone

Peralkaline Feldsphathic Igneous Rock

Ferruginous Sandstone (Ironstone)

Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)

Sandstone (with Feldspathic/Arkose qualities)

Arenite (primarily SiO2 with KAlSi3O8 components)

Goethite (Iron Ore)

Goethite (FeO(OH))

Sandstone with Magnetite and Iron Staining

Clastic Sedimentary Rock (contains Fe3O4 and Limonite/Hematite)

Sandstone

Clastic Sedimentary Rock (composed of SiO2 grains)

Halite

Halite (Sodium Chloride, NaCl)

Sodalite

Sodalite: Na8(Al6Si6O24)Cl2

Ferruginous Chert

Silicon dioxide with iron oxide impurities (SiO2 + Fe2O3)

Agate

Silicon dioxide (SiO2)

Schist with Schorl (Black Tourmaline)

NaFe3Al6(BO3)3Si6O18(OH)4 (Schorl)

Geode (unopened)

SiO2 - Chert-shelled concretion (mostly Quartz)

Agate

Silicon Dioxide (SiO2) - variety: Chalcedony

Banded Calcite (often sold as 'Mexican Onyx')

Calcite (Calcium Carbonate, CaCO3)

Jasper with Agate Inclusions

Jasper (Silicon Dioxide, SiO2) with Chalcedony/Agate

Chert (often called Flint)

Chert (Microcrystalline or cryptocrystalline Silica, SiO2)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Banded Agate

Agate (Cryptocrystalline Quartz, SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in a Secondary Formation

Quartz Vein / Milky Quartz

Silicon Dioxide (SiO2)

Aragonite / Calcite Geode

Calcium Carbonate (CaCO3)

Limonite Concretion

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

Sandstone (Water-worn Cobble)

Arenite (variable composition, primarily SiO2)

Sandstone (River Cobble)

Clastic sedimentary rock (primarily SiO2 with various lithic fragments)

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Gneiss

Gneiss

Sandstone (specifically Red Sandstone)

Arenite (primarily Quartz, SiO2)

Banded Sandstone (Liesegang Rings)

Sedimentary Arenite (SiO2 with FeO/Fe2O3 impurities)

Limestone (specifically Fossiliferous Limestone)

Calcium Carbonate (CaCO3)

Quartz Druzy on Geode Fragment

Silicon Dioxide (SiO2)

Red Sandstone (Hematitic)

Clastic sedimentary rock (SiO2 with Fe2O3 inclusions)

Blue Apatite

Apatite - Ca5(PO4)3(F,Cl,OH)

Quartz

Silicon Dioxide (SiO2)