Mineral (Man Made Glass, Not Natural)

Obsidian

Obsidian (volcanic glass), predominantly amorphous SiO₂

Chert (and associated river cobbles)

Silicon dioxide (SiO2)

Chalcedony (specifically Agate or Water-worn Quartzite)

Silicon Dioxide (SiO2)

Granite

Phaneritic Igneous Rock (composed mostly of Quartz, Feldspar, and Mica)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Chert

Microcrystalline Quartz (SiO2)

Rough Diamond

Diamond (pure Carbon, C)

Chert (and/or Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Granite

Phaneritic Felsic Igneous Rock

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Green Aventurine

Aventurine Quartz (SiO2 + Fuchsite mica)

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Sandstone

Arenite (SiO2 based clastic rock)

Ferruginous Sandstone (Ironstone)

Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)

Moonstone

Orthoclase Feldspar (formula: (K,Na)AlSi3O8)

Chert (Grey-Green Flint)

Microcrystalline silicon dioxide (SiO2)

Amethyst

SiO2 (Amethyst is a variety of Quartz)

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Banded Chert / Flint

Silicon dioxide (SiO2)

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock

Smoky Quartz (Tumbled)

Smoky Quartz (SiO2 - Silicon Dioxide)

Smoky Quartz

Silicon Dioxide (SiO2)

Smoky Quartz

Smoky Quartz (SiO2: Silicon Dioxide)

Pink Sapphire

Corundum (Al2O3 with trace Chromium and Iron)

Blue Topaz (facetted in jewelry)

Aluminum silicate fluoride hydroxide (Al2SiO4(F,OH)2)

Diamond

C (Carbon)

Sandstone (Yellow/Tan)

Clastic sedimentary rock (primarily SiO2 with iron oxide staining)

Citrine

Silicon Dioxide (SiO2) - Yellow Quartz variety

Massive Quartz (Yellow/Citrine variety)

Silicon Dioxide (SiO2)

Desert Rose (also known as Sand Rose)

Gypsum (CaSO4·2H2O) or Barite (BaSO4) with sand inclusions

Amethyst

Silicon dioxide (SiO2)

Amethyst

Amethyst (variety of Quartz, SiO2)

Jadeite and Mixed Gemstones (Ruby, Sapphire, Emerald)

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

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Green Aventurine

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

Green Aventurine

Silicon dioxide (SiO2) with inclusions of Fuchsite

Chert (specifically Black Chert or Flint)

Cryptocrystalline Quartz (SiO2)

Amethyst and Citrine (Quartz variants)

Silicon Dioxide (SiO2)

Chert (often colloquially called Flint)

Chert (Microcrystalline Quartz, SiO2)

Amethyst

Silicon Dioxide (SiO2) with trace Iron impurities