Organic Gemstone (Not A Rock)

Limestone with Chert or Siltstone bands

Sedimentary carbonate rock (CaCO3) often with siliceous impurities

Petrified Wood

Silicified Wood (primarily SiO2)

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Picasso Jasper (or Picasso Marble)

Metamorphosed Limestone (Calcium Carbonate, CaCO3, with impurities)

Jasper (specifically a banded or dark variety)

Silicon Dioxide (SiO2) with impurities

Chert / Flint

Cryptocrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Coquina Limestone (Fossiliferous Limestone)

Calcareous bioclastic sedimentary rock (CaCO3)

Limestone (specifically Fossiliferous or Crinoidal Limestone)

Calcium Carbonate (CaCO3) - Calcite Rock

Shale with Pyrite

Clastic sedimentary rock containing Iron Disulfide (FeS2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Fossilized Coral

Scleractinian Anthozoa (Fossilized Calcium Carbonate, CaCO3)

Chert (Chalcedony/Jasper)

Microcrystalline Quartz (SiO2)

Unakite

Epidotized Granite

Unakite

Epidotized Granite

Fossil Shell (Bivalve)

Class Bivalvia (Likely a member of the Ostreidae or Gryphaeidae family), CaCO3

Green Jasper (with Quartz veining)

Jasper (Silica-rich microcrystalline variety of Quartz), formula: SiO2

Petrified Wood

Silicified Wood (SiO2)

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Blue Quartzite

Quartzite (primarily SiO2) with inclusions like Dumortierite or Magnesio-riebeckite

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Petrified Wood

Silicified Wood (primarily SiO₂ / Silicon Dioxide)

Chert (White/Light Tan)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Jasper (specifically Yellow Jasper and Red Jasper)

Silicon Dioxide (SiO2) with iron oxide inclusions

Slate

Slate (Foliated metamorphic rock)

Chert (and/or Chalcedony)

Microcrystalline Silica (SiO2)

Chert (variations include Flint/Novaculite)

Chert (formula: SiO2)

Pickled Dragon Eggs (Fictional Interpretation: Purple Agate or Amethyst Geodes)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Carnelian (Chalcedony)

Silicon Dioxide (SiO2)

Pink Feldspar

Orthoclase Feldspar (KAlSi3O8)

Chert (Nodule)

Chert (Microcrystalline Quartz, SiO2)

Chert (Brown variety)

Silicon Dioxide (SiO2)

Chert (Jasper/Chalcedony)

Microcrystalline Silica (SiO2)

Chert (Flint)

Chert (Microcrystalline Quartz, SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2)

Chert (River Cobble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Fossiliferous Shale Matrix

Clastic Sedimentary Rock with Brachiopod or Mollusk shell fragments

Agate (Crazy Lace or Eye Agate)

Silicon Dioxide (SiO2)

Amber (Butterscotch/Egg Yolk Variety)

Succinite (Approx. C10H16O)

Green Quartz (Prasiolite)

Silicon Dioxide (SiO2) with trace impurities

Chert (and/or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Unakite (Epidotized Granite)

Epidote-Feldspar-Quartz Rock