Mineral, Organic Gemstone

Chert / Flint

Microcrystalline or cryptocrystalline quartz (SiO2)

Chert (specifically Tan/Yellow Chert)

Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)

Petrified Wood

Silicified wood (Quartz, SiO2)

Baroque Pearl

Biogenic Calcium Carbonate (Aragonite/Conchiolin)

Chert with Quartz/Calcite Vein

Microcrystalline Silica (SiO2)

Dendritic Agate / Moss Agate

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite

Moss Agate

Chalcedony (Silicon Dioxide, SiO2) with dendritic inclusions

Amber

Succinite (specifically for Baltic amber); C10H16O (Variable organic compound)

Sandstone (likely Arkose or Quartz Sandstone)

Arenite (SiO2 principal component)

Chert (Flint Nodules)

Chert (Microcrystalline Quartz, SiO2)

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Glauconitic Sandstone

Glauconitic Quartz Arenite

Amber

Fossilized Tree Resin (Amorphous Hydrocarbon)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)

Chalcedony (Common Opal variant)

Silicon dioxide (SiO2) with varying levels of hydration

Jasper Agate

Silicon dioxide (SiO2)

Shungite

Non-crystalline carbon (allotrope of carbon)

Amber (Simulated/Faturan Style)

Resin mix (Likely Phenolic/Celluloid if synthetic, Succinite if natural)

Chert / Flint

Chert (varieties include Flint)

Fossilized Sand Tiger Shark Tooth

Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)

Pyrite in Shale

Iron Disulfide (FeS2)

Mother of Pearl and Onyx

Aragonite (Mother of Pearl) and Chalcedony (Onyx)

Amber

Succinite (fossilized resin)

Moss Agate

Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)

Amber

Fossilized Tree Resin (C10H16O)

Megalodon Shark Tooth (Partial Fossil)

Otodus megalodon (fossilized in Calcium Phosphate/Apatite)

Bituminous Coal (with Anthracite or Vitrinite inclusion)

Organic-rich Sedimentary Rock (Carboniferous classification)

Jasper with Agate and Quartz Inclusions

Silicon Dioxide (SiO2) - Chalcedony / Quartz aggregate

Ironstone Concretion / Limonite Node

Goethite and Limonite (FeO(OH) nH2O)

Fossilized Coral

Cnidaria (Anthozoa), often replaced by Calcium Carbonate (CaCO3) or Silica (SiO2)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily Chalcedony or Quartz, SiO2)

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

Chert (Commonly known as Flint or Jasper when pigmented)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper variety)

Chert (SiO2)

Pearl

Calcium Carbonate (Aragonite) - CaCO3

Chert (Flint Nodules)

Microcrystalline Quartz (SiO2)

Chert (Brecciated Chert)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (primarily SiO₂ / Silicon Dioxide)

Chert (Flint)

Microcrystalline or cryptocrystalline quartz (SiO2)

Chert (Iron-rich variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)