Sedimentary Rock (Metamorphosed)

Chalcedony (Grey/White Agate)

Silicon Dioxide (SiO₂)

Yellow Quartz (Citrine or Yellow Jasper)

Silicon Dioxide (SiO2)

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Geode (Chert or Quartz Nodule)

Silicon Dioxide (SiO2)

Chalk

CaCO3 (primarily Calcium Carbonate), biogenic sedimentary rock

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (primarily SiO2 - Silicon Dioxide)

Sandstone (Weathered Coastal Boulder)

Arenite (composed primarily of SiO2)

Sandstone (likely Quartzose)

Arenite (SiO2 principal mineral)

Sandstone (likely Arkosic or Quartzose)

Sandstone (SiO2 with inclusions)

Sandstone (likely Fossiliferous)

Arenite / Sedimentum arenaceum

Sandstone

Arenite (primarily SiO2 with iron oxide cementation)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Pebble (river rock/beach pebble)

Pebble (clast size class)

Sandstone Concretion with Quartz Center

Sedimentary Clastic Rock (SiO2 matrix with Quartz core)

Sandstone (Ferruginous)

Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 staining)

Gneiss (Banded Gneiss)

Gneiss

Bituminous Coal (with Anthracite or Vitrinite inclusion)

Organic-rich Sedimentary Rock (Carboniferous classification)

Clear Quartz

Silicon Dioxide (SiO2)

Banded Gneiss

Gneiss (Metamorphic Rock)

Mica Schist

Mica Schist

Sandstone (Quartz-rich Pebble)

Arenite (primarily SiO2)

Gneiss with Quartz Veining

Gneiss (High-grade regional metamorphic rock)

Sandstone

Arenite (primarily Quartz, SiO2)

Greenstone / Glauconitic Siltstone

Metabasalt or Glauconite-rich Sedimentary Rock

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (Fe-rich SiO2)

Ferruginous Sandstone (Ironstone)

Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)

Sandstone (with biological crust)

Arenite (SiO2 based)

Almandine Garnet in Schist

Almandine Garnet (Fe3Al2(SiO4)3) in Mica Schist

Sandstone

Arenite (primarily SiO2 - Silicon Dioxide)

Banded Gneiss

Gneiss (Metamorphic Rock)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Clear Quartz Cluster

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartz (specifically Clear Quartz or Rock Crystal)

Silicon Dioxide (SiO2)

Chert with Desert Varnish

Cryptocrystalline Quartz (SiO2) with Manganese/Iron oxide coating

Clear Quartz

Quartz (Silicon Dioxide, SiO2)