Mineral Within Sedimentary Rock

Quartz Geode in Chert/Limestone Matrix

Silicon Dioxide (SiO2) within Sedimentary Host Rock

Chert (Jasper/Flint Pebble)

Microcrystalline quartz (SiO2)

Quartz Geode

Crystalline Silver Oxide (SiO2) in Calcareous Host

Gneiss with Quartz Vein

Metamorphic Gneiss

Chert (Jasper)

Silicon Dioxide (SiO2)

Turquoise

Turquoise - CuAl6(PO4)4(OH)8·4H2O

Sandstone with Ironstone Concretion

Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))

Ferruginous Siltstone

Siltstone with Magnetite/Hematite bands

Chert (Iron-stained)

Silicon Dioxide (SiO2) with Ferruginous impurities

Sandstone Concretion

Moqui Marble / Iron-oxide Concretion (SiO2 with Hematite/Goethite)

Carnelian (Orange Agate)

Silicon Dioxide (SiO2)

Gneiss

Gneiss (High-grade metamorphic rock)

Red Sandstone

Arenite (high iron oxide content)

Conglomerate

Conglomerate (clastic sedimentary rock)

Sandstone (Ferruginous)

Arenite with Iron oxide staining (SiO2 with Fe2O3)

Banded Chert (likely Flint or Jasper variety)

Silicon Dioxide (SiO2)

Thunder Egg (Agate/Jasper filled)

Chalcedony variety Agate/Jasper in a Rhyolitic matrix

Chert

Silicon Dioxide (SiO2)

Geode (Unopened Keokuk Geode)

Silicon Dioxide (SiO2) - Chalcedony / Quartz exterior

Sandstone (Stream-rounded Cobble)

Arenite (composed primarily of SiO2, Silica)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Carnelian

Carnelian (Silica/Chalcedony, SiO2)

Chert (within Limestone)

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Blue Lace Agate

Cryptocrystalline Quartz (SiO2) with trace minerals

Gneiss

Gneiss (High-grade Metamorphic Rock)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Sandstone (with Liesegang rings or Oxidation)

Arenite (primarily Quartz SiO2 with Iron Oxide Fe2O3 staining)

Amethyst

Silicon Dioxide (SiO2)

Concretion (Sandstone)

Carbonate-cemented Sandstone Concretion

Banded Pebble (Metamorphic Slate or Gneiss with Quartz Veining)

Metamorphic Rock with Quartz/Calcite Veins

Yellow Jasper

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite with Iron Oxide cement (SiO2 + Fe2O3)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Blue Calcite Sphere

Calcium Carbonate (CaCO3)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

River Rock

Sedimentary Rock (various compositions)

Conglomerate

Conglomerate rock

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Turquoise

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

Sandstone

Arenite (primarily Quartz Arenite)

Boulder Opal

Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)