Organic Gemstone (Often Associated With Sedimentary Sequences)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Citrine Quartz

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide, SiO2 with Iron impurities)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Blue Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Blue Calcite

Calcium Carbonate (CaCO3)

Quartzite

Quartzite

Magnetite / Hematite mix (Iron Ore)

Fe3O4 (Magnetite) / Fe2O3 (Hematite)

Fluorite (Rainbow Fluorite)

Calcium Fluoride (CaF2)

Fire Opal (in Matrix)

Hydrated Silica (SiO2·nH2O)

Milky Quartz

Silicon Dioxide (SiO2)

Chert (specifically Yellow or River Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Alexandrite

Chrysoberyl (BeAl2O4)

Limestone

Calcium Carbonate (CaCO3)

Rhodonite

Manganese silicate (Mn,Fe,Mg,Ca)SiO3

Chert (Nodule)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Quartz (likely Milky Quartz or Chalcedony)

Quartz (SiO2 - Silicon Dioxide)

Talc

Talc (Mg₃Si₄O₁₀(OH)₂)

Amazonite

Microcline (KAlSi3O8) with Trace Elements

Note: Image shows a biological specimen (Rat), not a rock. Representative geological equivalent: Galena (due to lead-grey colors in fur).

Galena (PbS)

Dendritic Opal (Common Opal)

Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions

Quartz (Milky/Clear Quartz)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Epidote Water-Worn Pebble

Epidote {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite/Iron oxide inclusions

Red Jasper

Silicon Dioxide with Hematite (SiO2 + Fe2O3)

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Raw Green Jasper

Silicon Dioxide (SiO2) with iron silicate inclusions

Quartz (Clear Quartz)

Silicon Dioxide (SiO2)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Ocean Jasper (Orbicular Jasper)

Spherulitic Chalcedony (SiO2)

Quartz (Milky/Crystalline)

Quartz (Silicon Dioxide, SiO2)

Quartz (Citrine or Iron-Stained)

Silicon Dioxide (SiO2)

Labradorite

Labradorite ((Ca, Na)(Al, Si)4O8)

Sandstone (likely Quartz Sandstone)

Arenite (composed primarily of SiO2)

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

Amazonite

KAlSi3O8 (Potassium Aluminum Silicate)

Citrine

Silicon dioxide (SiO2)

Quartz (Milky/Clear Quartz)

Silicon Dioxide (SiO2)