Sedimentary (Cryptocrystalline Quartz)

Chert (Iron-stained)

Chert (Cryptocrystalline Silica, SiO2)

Chalcedony (Common Opal variant)

Silicon dioxide (SiO2) with microcrystalline structure

Beach Pebble (likely Quartz or Chalcedony)

Silicon Dioxide (SiO2)

Dream Amethyst (Chevron Amethyst)

Silicon Dioxide (SiO2) with iron impurities and gamma radiation exposure

Quartz Pebble

Silicon Dioxide (SiO2)

Blue-dyed Quartz Druzy

Silicon Dioxide (SiO2) with artificial pigment

Clear Quartz

Silicon Dioxide (SiO2)

Green Aventurine

Silicon Dioxide (Quartz) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)

Chalcedony with Druzy Quartz Geode

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)

Jasper with Quartz Druzy

Silicon Dioxide (SiO2)

Chalcedony (specifically Agate or Common Opal variety)

Cryptocrystalline Silica (SiO2)

Clear Quartz (Rock Crystal)

Quartz (SiO₂)

Agate

Banded Chalcedony (SiO2)

Banded Agate (specifically Lace Agate type)

Silicon Dioxide (SiO2)

Pyrite on Quartz matrix

Iron Disulfide (FeS2) on Silicon Dioxide (SiO2)

Quartz Pebble (Hag Stone / Adder Stone)

Silicon Dioxide (SiO2)

Dalmation Stone

Peralkaline Rock (mixed silicate minerals)

Yellow Chalcedony (Agate)

Silicon Dioxide (SiO2)

Jasper

Silicon dioxide (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Quartz with Mica inclusions (likely Schist or Gneiss host)

Silicon Dioxide (SiO2) with Phyllosilicates (KAl2(AlSi3O10)(OH)2)

Quartz Vein in Host Rock (Likely Slate or Shale)

Hydrothermal Quartz (SiO2) in Pelitic host rock

Pyrite in Matrix (Fool's Gold)

Iron Sulfide (FeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Banded Agate (Pink/Peach Chalcedony)

Agate (Silicon Dioxide, SiO2)

Quartz (Milky or Cloudy Quartz)

Silicon Dioxide (SiO2)

Turquoise

Hydrated phosphate of copper and aluminum, CuAl6(PO4)4(OH)8·4H2O

Limonite (Ochreous)

FeO(OH)·nH2O (Hydrated Iron Oxide)

Flint (Chert)

Silicon Dioxide (SiO2)

Clear Quartz crystals on a Matrix base (Geode fragment)

Silicon Dioxide (SiO2)

Quartz (likely a clear or rock crystal variety)

Quartz (SiO2 - Silicon Dioxide)

Orange Quartzite (Tumbled)

Quartzite (SiO2)

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Banded Agate (Yellow Agate)

Silicon Dioxide (SiO2)

Chert (Fossiliferous)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert (Nodule)

Chert (Silicon Dioxide, SiO2)

Kyanite in Quartz

Al2SiO5 in SiO2

Purple Dyed Agate Geode (Banded Chalcedony)

Silicon Dioxide (SiO2) - variety: Agate

Quartz

Quartz (Silicon Dioxide - SiO2)