None

Quartzite

Quartzite (primarily SiO2)

Amber

Succinite (a specific high-quality amber from the Baltic)

Quartzite

Quartzite (SiO2)

Quartzite Pebble

Quartzite (primarily SiO2)

Glass Nugget (Tumbled Glass)

Amorphous Silicon Dioxide (SiO2) with additives

River Stone (Quartzite)

Metamorphosed Sandstone (SiO2)

Obsidian

Obsidian (principally SiO2, 70% or more silica)

Amber

Succinite (approximate formula C10H16O)

Quartzite (with Iron Staining)

Metamorphosed Quartz Sandstone (SiO2)

Quartzite pebble

Quartzite (SiO2)

Quartzite

Quartzite (primarily SiO2)

Snowflake Obsidian

Volcanic glass with Spherulite inclusions (SiO2)

Obsidian

Obsidian (Volcanic Glass)

Obsidian

Volcanic Glass (predominantly SiO2)

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Obsidian (Black Obsidian)

Obsidian (Volcanic Glass)

Dyed Pink Dragon Vein Agate

Silicon Dioxide (SiO2) with artificial dye additives

Quartz (Clear Quartz)

Silicon Dioxide (SiO2)

Quartz Pebbles

Silicon Dioxide (SiO2)

Fossiliferous Limestone

Limestone (CaCO3 - Calcium Carbonate)

Quartz Geode (with Calcite influence)

Silicon Dioxide (SiO2) with possible Calcium Carbonate (CaCO3)

Sandstone (likely Arkosic)

Clastic Sedimentary Rock

Clear Quartz

Silicon Dioxide (SiO2)

Agatized Fossil (Druzy Agate)

Silicon Dioxide (SiO2) replacing organic matter

Agate

Chalcedony (cryptocrystalline variety of Quartz, SiO2)

Amethyst (as seen in jewelry)

Amethyst (Silicon Dioxide SiO2 + Fe4+)

Green Quartzite (River Stone)

Metamorphic Quartz (SiO2) with inclusions (typically Fuchsite or Chlorite)

Milk Quartz (White Quartz)

Silicon Dioxide (SiO2)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Red Quartzite River Stone

Quartzite (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert (Jasper/Agate variety)

Microcrystalline quartz (SiO2)

Quartzite Cobble with Quartz Vein

Metamorphic Quartzite (SiO2)

Aventurine

Silicon Dioxide (SiO2 with inclusions of Fuchsite mica)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Clear Quartz Cluster

Silicon Dioxide (SiO2)

Dyed Chalcedony (Agate)

Silicon Dioxide (SiO2) with artificial pigment

Red Quartzite / Metasandstone River Pebble

Quartzite (primarily SiO2 with hematite inclusions)

Quartzite with Hematite staining

Quartzite (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Tiger's Eye

Tiger's eye (Pseudomorph of Quartz after Crocidolite), SiO2

Milky Quartz

Quartz (Silicon Dioxide, SiO2)