Sedimentary (Microcrystalline Silicate)

Clear Quartz crystals on a Matrix base (Geode fragment)

Silicon Dioxide (SiO2)

Agate Geode

Chalcedony (cryptocrystalline SiO2)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Petrified Wood

Silicified Wood (SiO2)

Boulder Opal

Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Blue Banded Agate (Dyed)

Silicon Dioxide (SiO2) - variety of Chalcedony

Chalcedony (Quartz Nodule)

Silicon Dioxide (SiO2)

Yellow Chalcedony (Agate Pebble)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Mixed Quartz and Jasper Pebbles

Silicon Dioxide (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Green Aventurine

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

Jasper (Red Jasper)

Jasper (SiO2 - Silicon Dioxide with iron inclusions)

Clear Quartz Crystal

Quartz (Silicon Dioxide, SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Peach/Orange variety)

Silicon Dioxide (SiO2)

Quartz Vein in Sedimentary Matrix

Silicon Dioxide (SiO2) with host rock

Fossilized Shark Tooth (Basal Bone)

Otodus sp. (Mineralized Hydroxyapatite)

Banded Chert (Jasper)

Silicon Dioxide (SiO2)

Opal (Precious Opal)

Hydrated Silica (SiO2·nH2O)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Agate (Chalcedony)

Cryptocrystalline Silica or Silicon Dioxide (SiO2)

Clear Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Ferruginous Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions

Clear Quartz (Rock Crystal Fragments)

Silicon Dioxide (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Banded Agate (specifically Sardonyx or Carnelian Agate)

Silicon Dioxide (SiO2) - Chalcedony variety

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in a Secondary Sedimentary/Volcanic cavity

Sandstone Concretion

Clastic sedimentary rock (primarily Quartz SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Banded Agate (with Quartz Geode Center)

Silicon Dioxide (SiO2)

Carnelian

Carnelian Chalcedony (SiO2)

Jasper

Jasper (Cryptocrystalline variety of Quartz, SiO2)

Banded Gneiss with Quartz Vein

Foliated Metamorphic Rock (Gneiss)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Chert (often called Flint or Jasper)

Silicon Dioxide (SiO2)

Rough Quartz (or Quartzite pebble)

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Agate (specifically Lace Agate or Banded Agate)

Silicon Dioxide (SiO2)

Banded Black Onyx (Chalcedony)

Silicon Dioxide (SiO₂)