Sedimentary Rock (Technically A Microcrystalline Quartz Mineral Aggregate)

Quartz Druzy on Geode Fragment

Silicon Dioxide (SiO2)

Gneiss

Gneiss (a type of metamorphic rock)

Chert (Jasper)

Microcrystalline Quartz (SiO2)

White Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily Quartz - SiO2)

Chert (and its variety Flint)

Silicon dioxide (SiO2) / Microcrystalline quartz

Quartz

Silicon Dioxide (SiO2)

Sandstone (Quartzite texture)

Arenite (SiO2 secondary)

Chert (Gravel pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) - Impure Cryptocrystalline Quartz

Chert (specifically Jasper or Flint variety)

Cryptocrystalline Quartz (SiO2)

Quartz with Iron Staining

Silicon Dioxide (SiO2) with Ferruginous Oxides

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (likely Calcareous or Micaceous)

Clastic sedimentary rock (primarily Quartz with Cementing Agents)

Quartz Geode

Silicon Dioxide (SiO2) in Geode form

Quartz / Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Chert / Flint

Silicon Dioxide (SiO2)

Agate Geode

Silicon Dioxide (SiO2)

Chert (Field-collected variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Green Aventurine

Quartzite with Fuchsite inclusions (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)

Milky Quartz

Silicon Dioxide (SiO2)

Chert Nodule

Chert (Cryptocrystalline variety of Quartz, SiO2)

Red Siltstone

Siltstone (primarily quartz and feldspar sized 0.0039 to 0.0625 mm)

Chert (Flinty variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Nodular Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper)

Microcrystalline Quartz (SiO2) with iron oxide impurities

Obsidian

Obsidian (Volcanic Glass)

Chert (and Flint)

Silicon dioxide (SiO2) - Microcrystalline quartz

Quartz Pebble

Silicon Dioxide (SiO2)

Chert (Arrowhead or Projectile Point)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Jasper with Quartz inclusions

Silicon Dioxide (SiO2) with impurities

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Crushed Limestone

Calcite-rich Sedimentary Rock (CaCO3)

Red Jasper

Jasper (SiO2) with Hematite (Fe2O3) inclusions

Chert Pebble

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variant Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variously identified as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Gravel specimen)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Nodule)

Chert (Microcrystalline Quartz, SiO2)

Chert (Chert / Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Pink/Red variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)