Organic (Non Geological)

River Rock (likely Quartzite or Chert)

Quartzite (primarily SiO2)

Sandstone (Quartzose)

Arenite (SiO2 principal)

River Pebble (Quartz-rich)

Silicon Dioxide (SiO2) with various inclusions

Sandstone (specifically Arkose or Ferruginous Sandstone)

Sandstone (SiO2 with iron oxide inclusions)

River Pebble (Gneiss or Quartzite variant)

Course-grained Metamorphic Rock (likely SiO2 dominant)

Dendritic Agate or Spotted Quartzite

Silicon Dioxide (SiO2) with inclusions

Quartz Pebble (Milky Quartz)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Gold

Native Gold (Au)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Basalt with Limonite stains

Extrusive mafic igneous rock; Limonite (FeO(OH)·nH2O)

Gastropod Fossil (Snail Internal Mold)

Gastropoda; internal mold (steinkern), often composed of Calcium Carbonate (CaCO3) or Silica (SiO2)

Iron-stained Quartzite

Recrystallized Quartz (SiO2) with Hematite/Limonite staining

Basalt

Basalt (Aphanitic Mafic Igneous Rock)

Basalt

Mafic Volcanic Rock

Sandstone

Arenite (primarily Quartz, SiO2)

Gold Ore

Native Gold in Quartz (Au)

Granite

Phaneritic Plutonic Felsic Rock (SiO2, KAlSi3O8, NaAlSi3O8, CaAl2Si2O8)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Granite

Intrusive Igneous Rock (composed primarily of Quartz: SiO2, Feldspar: KAlSi3O8, and Mica: KAl2(AlSi3O10)(OH)2)

Red Jasper

Silicon Dioxide (SiO2)

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Black Onyx

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Obsidian

Obsidian (Volcanic Glass, SiO2 dominated)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Garnet (likely Almandine or Pyrope)

Garnet Group (Fe3Al2Si3O12 or Mg3Al2Si3O12)

Quartz (specifically Milky or Clear Quartz)

Silicon Dioxide (SiO2)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Crystal Point/Fragment)

Silicon Dioxide (SiO2)

White Quartz (Tumbled)

Quartz (Silicon Dioxide, SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Black Onyx

Silicon dioxide (SiO2) with parallel banded structure

Quartz

Silicon Dioxide (SiO2)

Milky Quartz (or Vein Quartz)

Silicon Dioxide (SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Quartz (Clear Quartz and Rose Quartz variants)

Silicon Dioxide (SiO2)

Green Quartzite

Quartzite (SiO2)

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)