Organic Gemstone (Sedimentary Classification)

Jasper

Silicon dioxide (SiO2) with iron oxide inclusions

Banded Agate (specifically Lake Superior Agate or similar)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Red Jasper

Jasper (Silicon Dioxide based crypto-crystalline Quartz with Iron inclusions)

Jasper

Jasper (Silicon Dioxide, SiO2)

Red Jasper

Jasper (Silicon Dioxide with Iron Oxide impurities, SiO2)

Quartz (specifically Milky or Clear Quartz)

Silicon Dioxide (SiO2)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Coral (Precious Coral)

Corallium rubrum (Red Coral), Paracorallium japonicum (Momo Coral), Pleurocorallium elatius (Sardinian Coral), various other species within the Corallidae family. Chemically, it's primarily Calcium Carbonate (CaCO 3 ).

Almandine Garnet (weathered)

Almandine (Fe3Al2(SiO4)3)

Amethyst or Smoky Quartz Geode Slice

Crystalline Silicon Dioxide (SiO2) with iron impurities

Carnelian Agate

Chalcedony (SiO2) with iron oxide inclusions

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Jasper

Cryptocrystalline Quartz (SiO2)

Carnelian

Carnelian (a variety of Chalcedony), SiO2 (Silicon Dioxide)

Druzy Chalcedony/Quartz on Fluorite core

Silicon Dioxide (SiO2) on Calcium Fluoride (CaF2)

Pyrite and Sunstone

Iron Sulfide (FeS2) and Plagioclase Feldspar ((Ca,Na)Al(Al,Si)Si2O8)

Chalcedony

Cryptocrystalline Quartz (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Jasper

Silicon dioxide (SiO2)

Almandine Garnet in Matrix

Almandine (Fe3Al2(SiO4)3)

Chert / Jasper

Silicon Dioxide (SiO2)

Dalmatian Stone

Dalmatian Jasper (Aplitic Rock)

Green Chalcedony

Silicon Dioxide (SiO2) with trace minerals

Turquoise

Hydrated copper and aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O)

Shale or Argillite

Shale (fine-grained clastic sedimentary rock) or Argillite (low-grade metamorphic rock derived from shale)

Clear Quartz

Silicon Dioxide (SiO2)

Tumbled Carnelian and Quartz Mix

Silicon Dioxide (SiO2) with iron oxide impurities

Quartz (Iron-stained or Milky)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Carnelian

Carnelian (Silicon Dioxide - SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (primarily SiO₂ - Silicon Dioxide)

Turquoise

Hydrous phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Jasper and Chert Conglomerate

Ferruginous Microcrystalline Quartz (SiO2)

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Red Jasper

Silicon Dioxide (SiO2)

Black Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Garnet (Almandine)

Almandine (Fe3Al2(SiO4)3)

Petoskey Stone (Fossilized Coral)

Hexagonaria percarinata (CaCO3)