Sedimentary (Microcrystalline Quartz)

Quartz (Iron-stained or Milky)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartzite

Quartzite (SiO2)

Orange Quartzite (River Pebble)

Quartzite (SiO2 with iron oxide impurities)

Quartz (likely a macrocrystalline variety like milky quartz or smoky quartz, given the appearance in the image)

Quartz (SiO₂ - Silicon Dioxide)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz Pebble (Iron-stained)

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz with Fe2O3 staining)

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz

Quartz (SiO2, Silicon Dioxide)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Milky/Gravel variety)

Silicon Dioxide (SiO2)

Quartzite

Quartzite (SiO2)

Agate

Silicon Dioxide (SiO2)

Black Obsidian

Volcanic Glass (predominantly SiO2, Silicon Dioxide)

Quartzite Pebble

Quartzite (principally SiO2)

Quartzite

Quartzite (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite Pebble (with Quartz veins)

Quartzite (SiO2)

Quartzite Pebbles

Quartzite (SiO2)

Quartzite

Quartzite (SiO2)

Chrysocolla in Quartz (Quantum Quattro variant)

Hydrated copper silicates (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O) often mixed with SiO2

Petrified Wood

Silicified Wood (SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Orange Quartzite (Tumbled Beach Pebble)

Quartzite (primarily SiO2)

Quartzite

Quartzite (primarily Silicon Dioxide, SiO2)

Quartz

Quartz (SiO₂)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Botryoidal Goethite on Quartz

Goethite (α-Fe3+O(OH)) on Quartz (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Crazy Lace Agate

Silicon Dioxide (Microcrystalline Quartz) - SiO2

Indian Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Crazy Lace Agate

Banded Chalcedony (Microcrystalline Quartz, SiO2)

Carnelian Agate (with Quartz/Chalcedony)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Quartz (Milky/Crystal Variety)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Quartz (Float/Abraded)

Quartz (SiO₂)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)