Organic (Non Rock)

River Siltstone / Mudstone Pebble

Siltstone (composed of mixed silicate and carbonate minerals)

Quartzite

Quartzite (SiO2)

Travertine

Travertine (a terrestrial form of Limestone, CaCO3)

Fossil Shark Tooth

Selachii (fossilized dentition)

Red Jasper or Ferruginous Chert

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Cullet Glass (Slag Glass)

Amorphous Silicon Dioxide (SiO2) with metallic oxide impurities

Green Chert

Microcrystalline Quartz (SiO2)

Quartzite

Quartzite (SiO2)

Fossil Coral

Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)

Chert (River Cobble)

Chert (Cryptocrystalline Quartz, SiO2)

Rounded granite pebble

Granite, chiefly quartz, feldspar, and mica; approximate composition SiO₂-rich felsic rock

Manganese Dendrite on Siltstone

Manganese Oxide (pyrolusite or psilomelane) Dendrites

Fossilized Shell

Invertebrate fossil (Bivalvia or Brachiopoda)

Chert (Jasper-rich)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Quartzite

Quartzite (primarily SiO2)

Chert with Quartz Vein

Silicon dioxide (SiO2)

Breccia

Breccia (Clastic Sedimentary Rock)

Quartzite

Quartzite (SiO2-dominant rock)

Fossiliferous Limestone

Calcium Carbonate (CaCO3)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Quartzite (Pink/Red variety)

Quartzite (SiO2 with iron oxide impurities)

Anthracite Coal

Anthracite (Carbon-rich metamorphic rock)

Quartzite pebble

Quartzite (SiO2 dominated)

Chert Pebble Map

Microcrystalline Quartz (SiO2)

Obsidian (Apache Tear)

Amorphous Volcanic Glass (SiO2)

Slag

Glassy silicate byproduct (anthropogenic material)

Grey Quartzite Pebble

Quartzite (primarily SiO2)

Sandstone with Liesegang Rings

Liesegang-banded Sandstone

Beach Quartzite Pebble

Quartzite (primarily SiO2)

Sandstone with Iron Staining

Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)

Red Quartzite

Quartzite (primarily SiO2)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Snowflake Obsidian

Volcanic glass containing Spherulite inclusions (primarily Cristobalite, SiO2)

Chert (Yellow Jasper/Flint)

Silicon dioxide (SiO2) - Cryptocrystalline Quartz

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions

Yellow Quartzite River Stone

Quartzite (primarily SiO2)

Chert (Field Stone)

Silicon Dioxide (SiO2)

Chert (and Jasper)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Quartzite variety)

Microcrystalline Silica (SiO2)

Chert (and its variety Flint)

Silicon dioxide (SiO2) / Microcrystalline quartz