Gemstone

Raw Corundum (Sapphire/Ruby variant)

Aluminum oxide (Al2O3)

Quartz / Rock Crystal

Silicon Dioxide (SiO2)

Obsidian

Volcanic glass (high silica volcanic rock)

Chert (often called Jasper or Flint in this color variety)

Silicon Dioxide (SiO2)

Quartz (Druzy or Crystalline variety)

Silicon Dioxide (SiO2)

Quartz (Grain/Fragment)

Silicon Dioxide (SiO2)

Quartz Crystal (specifically Rock Crystal)

Silicon Dioxide (SiO2)

Garnet

Garnet Group (Silicate mineral); general formula X3Y2(SiO4)3

Orthoclase Feldspar

KAlSi3O8 (Potassium Aluminum Silicate)

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz (Crystalline Cluster)

Silicon Dioxide (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Quartz (likely Rose or Milky Quartz)

Silicon Dioxide (SiO2)

Quartz (Granular)

Silicon Dioxide (SiO2)

Obsidian

Extrusive igneous volcanic glass

Garnet in Schist (Garnetiferous Micaceous Schist)

Almandine Garnet, Fe3Al2(SiO4)3

Fluorite and Red Jasper

Fluorite (Calcium Fluoride, CaF2) and Red Jasper (Silicon Dioxide, SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Obsidian

Volcanic Glass (Amorphous Silica)

Chert (Jasper/Flint variation)

Chert (SiO2)

Turquoise and Hematite

CuAl6(PO4)4(OH)8·4H2O (Turquoise) and Fe2O3 (Hematite)

Rough Quartz

Quartz (Silicon Dioxide, SiO2)

Chalcedony (specifically Agate or Carnelian pebble)

Chalcedony (Microcrystalline Quartz, SiO2)

Pegmatite with Muscovite

Granitic Pegmatite (KAl2(AlSi3O10)(OH)2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz (Raw Chunk)

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Almandine Garnet

Almandine (Fe3Al2Si3O12)

Blue Chalcedony

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with goethite or iron oxide inclusions

Red Jasper

Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Milky Quartz

Silicon Dioxide (SiO2)