Man Made Glass (Not A Natural Rock Or Mineral)

Pyrite in Shale

Iron Sulfide (FeS2) in Sedimentary Matrix

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

White Quartz (Tumbled)

Silicon Dioxide (SiO2)

Black Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone

Arenite (primarily SiO2)

Garnet Beads

Garnet Group (complex nesosilicates, e.g., Almandine Fe3Al2(SiO4)3)

Diamond

C (Carbon)

Fossiliferous Chert with Brachiopod Impression

Chert (SiO2) containing Brachiopoda fossil remains

Massive Quartz (Yellow/Citrine variety)

Silicon Dioxide (SiO2)

Botryoidal Quartz / Calcite Geode crust

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

Snowflake Obsidian

Volcanic glass containing Spherulite inclusions (primarily Cristobalite, SiO2)

Amethyst

Amethyst (variety of Quartz, SiO2)

Basalt (River Pebble)

Mafic volcanic rock (primarily Plagioclase feldspar and Pyroxene)

Jadeite and Mixed Gemstones (Ruby, Sapphire, Emerald)

Jadeite (NaAlSi2O6), Corundum (Al2O3), Beryl (Be3Al2(Si6O18))

Quartz (Milky or Cloudy variety)

Silicon Dioxide (SiO2)

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Quartzite River Rock

Quartzite (primarily SiO2)

Feldspar

Potassium Feldspar (KAlSi3O8)

Quartz (Druzy)

Silicon Dioxide (SiO2)

Green Aventurine

Quartzite with Fuchsite (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)

Green Aventurine

Silicon dioxide (SiO2) with inclusions of Fuchsite

Amethyst and Citrine (Quartz variants)

Silicon Dioxide (SiO2)

Quartz (River Stone)

Silicon Dioxide (SiO2)

Chert (specifically Black Chert or Flint)

Cryptocrystalline Quartz (SiO2)

Quartz Vein in River Siltstone

Crystalline Quartz (SiO2) in Siliclastic Matrix

Chert (often colloquially called Flint)

Chert (Microcrystalline Quartz, SiO2)

Milky Quartz (among River Rock)

Quartz (Silicon Dioxide, SiO2)

Banded Quartz

Silicon Dioxide (SiO2)

Muscovite Mica (Golden/Yellow variety)

KAl2(AlSi3O10)(F,OH)2

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Sandstone (likely Arkose or Quartz Sandstone)

Arenite (SiO2 + varied clasts)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (likely Calcareous or Micaceous)

Clastic sedimentary rock (primarily Quartz with Cementing Agents)

Sandstone

Arenite (primarily SiO2)

Quartz Veinated Sandstone or Siltstone

Silicon Dioxide (SiO2) within a clastic sedimentary matrix

Sandstone

Arenite (primarily SiO2)

Amethyst (Quartz Cluster)

Silicon Dioxide (SiO2) with iron impurities

Quartz Geode

Silicon Dioxide (SiO2)

Snowflake Obsidian

Volcanic glass with Cristobalite inclusions (70–75% SiO2)