Man Made Rock (Sedimentary Analogue)

Bored Siltstone (Holey Rock)

Siltstone with Pholad borings (Lithophaga/Pholadidae trace fossils)

Sandstone (Ferruginous)

Sandstone (SiO2 with iron oxide inclusions)

River Stone / Pebble

Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)

Turquoise

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

Gneiss

Gneiss

Chert Concretion with Iron Oxide Staining

Microcrystalline Quartz (SiO2)

Limonite with Hematite

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

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Carnelian (Red Agate)

Silicon dioxide (SiO2) with iron oxide impurities

Chert Nodule in Limestone

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3)

Red Jasper

Silicon dioxide (SiO2) with iron oxide inclusions

Quartz (Druzy)

Silicon Dioxide (SiO2)

Agate

Silicon dioxide (SiO2)

Banded Calcite (often sold as 'Mexican Onyx')

Calcite (Calcium Carbonate, CaCO3)

Schist with Schorl (Black Tourmaline)

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

Agate

Silicon Dioxide (SiO2) - variety: Chalcedony

Geode (unopened)

SiO2 - Chert-shelled concretion (mostly Quartz)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Banded Agate

Agate (Cryptocrystalline Quartz, SiO2)

Jasper with Agate Inclusions

Jasper (Silicon Dioxide, SiO2) with Chalcedony/Agate

Quartz Vein / Milky Quartz

Silicon Dioxide (SiO2)

Aragonite / Calcite Geode

Calcium Carbonate (CaCO3)

Quartz Geode

Silicon Dioxide (SiO2) in a Secondary Formation

Marble (White)

Metamorphosed Limestone (mainly CaCO3)

Limonite Concretion

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

Milky Quartz

Quartz (Silica / Silicon Dioxide), SiO2

Red Sandstone

Arenite (primarily Quartz, SiO2, with Iron Oxide cementing agent)

Sandstone

Clastic Sedimentary Rock (composed of SiO2 grains)

Quartz Druzy on Geode Fragment

Silicon Dioxide (SiO2)

Goethite (Iron Ore)

Goethite (FeO(OH))

Sandstone (Red/Brown)

Arenite (composed primarily of SiO2)

Halite

Halite (Sodium Chloride, NaCl)

Dalmatian Stone

Peralkaline Feldsphathic Igneous Rock

Jasper

Chalcedony (SiO2)

Blue Apatite

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

Pyrite in Quartz

Iron Sulfide (FeS2) in Silicon Dioxide (SiO2)

Ferruginous Sandstone (Ironstone)

Sedimentary rock with high iron oxide content (Fe2O3 / FeO(OH))

River Agate (Chert/Chalcedony)

Cryptocrystalline Quartz (SiO2)

Ferruginous Chert

Silicon dioxide with iron oxide impurities (SiO2 + Fe2O3)

Chert (Jasper)

Sedimentary Cryptocrystalline Quartz (SiO2)

Red Sandstone (Hematitic)

Clastic sedimentary rock (SiO2 with Fe2O3 inclusions)