Quartz

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Iron-Stained Quartz Pebble

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Clear Quartz

Silicon Dioxide (SiO2)

Rutilated Quartz

Silicon Dioxide (SiO2) with Titanium Dioxide (TiO2) inclusions

Sandstone

Arenite (primarily Quartz, SiO2)

Granitic Pegmatite

Granitic Pegmatite with Quartz and Feldspar

Druzy Chalcedony/Quartz on Fluorite core

Silicon Dioxide (SiO2) on Calcium Fluoride (CaF2)

Graphic Granite

Graphic Granite (Granitic Pegmatite), typically KAlSi3O8 (Feldspar) + SiO2 (Quartz)

Quartz Geode

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

Quartz (specifically Milky/White Quartz)

Silicon Dioxide (SiO2)

Tiger's Eye (Rough)

Pseudomorph of Quartz after Crocidolite (SiO2 with FeOOH inclusions)

Quartzite

Quartzite (chiefly SiO2)

Chevron Amethyst

Silicon Dioxide (SiO2) with iron impurities

Rutilated Quartz

Silicon Dioxide (SiO2) with Titanium Dioxide (TiO2) inclusions

Arfvedsonite in Quartz

Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar

Pyrite in Quartz

FeS2 (Iron Pyrite) with SiO2 (Quartz)

Terrazzo (Man-made Composite)

Cementitious or Resin-bound Lithic Composite

Unakite (or Epidote-rich Granite)

Unakite (composed of Epidote {Ca2(Al, Fe)3(SiO4)3(OH)}, Pink Orthoclase Feldspar {KAlSi3O8}, and Quartz {SiO2})

Chert (Arrowhead Debitage or Spall)

Silicon Dioxide (SiO₂)

Unakite

Epidotized Granite

Limonitic Sandstone with Inclusion

Limonitic Quartz Sandstone (primarily SiO2 with FeO(OH)·nH2O)

Chert (Arrowhead Artifact)

Chert (SiO2)

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate)

Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement

Lepidolite in Quartz (or Lepidolite Ore)

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2) in Quartz (SiO2)

Chert (Flint variety)

Chert (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified wood (primarily Silicon Dioxide, SiO2)

Muscovite Schist with Quartz

KAl2(AlSi3O10)(OH)2 in Schistose matrix

Fossiliferous Chert with Brachiopod Impression

Chert (SiO2) containing Brachiopoda fossil remains

Graywacke (Sandstone)

Graywacke Sandstone

Aquamarine

Beryl (Be3Al2Si6O18)

Granite

Intrusive Felsic Igneous Rock

Granite

Granite

Granite

Phaneritic Igneous Rock (Granite)

Sandstone with Quartz Vein

Arenite with Quartz (SiO2) Infilling

Gneiss

Gneiss (Metamorphic rock)

Granite (Thin Section)

Granite (Felsic Plutonic Rock)

Aquamarine

Beryl (Be3Al2Si6O18)

Pink Orthoclase Feldspar with Dendrites

Orthoclase (KAlSi3O8) with Manganese Oxide dendrites

Granite

Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, NaAlSi3O8)

Granite

Phaneritic Igneous Rock (Granite)

Granitic Gneiss

Gneiss (Metamorphic rock of granitic composition)