Sedimentary Rock (Technically A Microcrystalline Quartz Mineral Aggregate)

Limestone

Calcareous sedimentary rock (CaCO3)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Conglomerate

Conglomerate (a clastic sedimentary rock)

White Quartz Pebble (Milky Quartz)

Silicon Dioxide (SiO2)

Yellow Quartzite Pebble

Quartzite (SiO2)

Dalmatian Jasper / Dalmatian Stone

Peralkaline Rock (Silicon Dioxide with Amphibole inclusions)

Dyed Agate (Tumbled)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Gneiss

Gneiss (High-grade Metamorphic Rock)

Dendritic Agate

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert Nodule

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Limestone (Grey and White specimens)

Calcium Carbonate (CaCO3)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Chert (Nodule)

Microcrystalline Quartz (SiO2)

Chert (often called Flint)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Mixed collection of Quartz varieties, Chalcedony, and metamorphic pebbles

Mixed gemstones (primarily Silicon Dioxide - SiO2)

Red Jasper

Jasper (Silicon Dioxide with iron oxide inclusions), SiO2

Chert (often found as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Jasper (specifically Bloodstone/Heliotrope or Dark Green Jasper)

Cryptocrystalline Quartz (SiO2) with inclusions

Wishing Stone (Gneiss or Basalt with Quartz Vein)

Gneiss or Metabasalt (with a Quartz or Calcite intrusion)

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sandstone (Muddy/Silty Variety)

Arenite with high silt/clay content (clastic sedimentary rock)

Chert (and Flint)

Cryptocrystalline Quartz (SiO2)

Clear Quartz crystals on a Matrix base (Geode fragment)

Silicon Dioxide (SiO2)

Snowflake Obsidian

Spherulitic Volcanic Glass (primarily SiO2)

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Quartz (Milky/Vein Quartz)

Silicon Dioxide (SiO2)

Riverstone (Quartzite or Siltstone cobble)

Quartzite (primarily SiO2)

Chert (specifically Black Chert or Flint)

Cryptocrystalline Quartz (SiO2)

River Quartzite or Chert Pebble

Quartzite (primarily Silicon Dioxide - SiO2)

Ferruginous Quartz (Iron-stained Quartzite)

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variations include Flint)

Chert (SiO2)

Geode (Unopened)

Silica-rich concretion (SiO2)

Chert (with Quartz vein)

Chert (Silicon Dioxide, SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Druzy Quartz on Chalcedony Matrix

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula: SiO2)