Anthropogenic Specimen (Man Made)

Devil's Toenail (Fossil Oyster)

Gryphaea arcuata (Calcium Carbonate, CaCO3)

Rhyolitic Tuff

Rhyolitic Tuff / Pyroclastic rock

Chert (often called Flint when dark or worked)

Cryptocrystalline silica (SiO2)

Yellow Quartzite Pebble

Quartzite (SiO2 with Iron Oxide staining)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Quartzite River Pebble

Quartzite (primarily SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Granite Pebble

Granite (composition of Quartz, Alkali Feldspar, and Plagioclase)

Dyed Agate

Silicon Dioxide (SiO2)

Chert (Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz pebble

Silicon dioxide (SiO2)

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartzite (Ferruginous)

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone (likely Arkosic)

Clastic Sedimentary Rock (primarily SiO2 with Feldspar)

Sandstone (likely Fossiliferous Sandstone)

Clastic sedimentary rock (primarily SiO2)

Granite Pebble

Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Quartz / Common Opal

Silicon Dioxide (SiO2)

Quartz (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Chert (Basanite / Flint)

Microcrystalline silica (SiO2)

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

Yellow Quartzite Pebble

Quartzite (SiO2)

Quartzite River Rock

Quartzite (Silicon Dioxide, SiO2)

Chert (Beach Pebble)

Microcrystalline Quartz (SiO2)

Stream Pebble (Basalt/Greywacke)

Mafic Igneous Rock (Fine-grained)

Quartz (River Pebble)

Silicon Dioxide (SiO₂)

Chert (Iron-stained)

Microcrystalline quartz (SiO2)

Quartzite pebble

Quartzite (primarily SiO2)

Quartzite (River Pebble)

Quartzite (SiO2)

Quartz Pebble

Silicon dioxide (SiO2)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Gold (10K Alloy)

Aurum (Au) with alloying metals (Cu, Ag, Zn)

Quartzite Cobble

Quartzite (primarily SiO2)

Sandstone

Arenite (primarily SiO2)

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Brown Agate

Silicon Dioxide (SiO2)

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

White Quartz (Tumbled)

Silicon Dioxide (SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Amethyst

Silicon Dioxide with Iron impurities (SiO2)