Organic Gemstone (Not A Mineral)

Sandstone (likely Arkose or Quartz Sandstone)

Arenite (SiO2 principal component)

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Chert (Flint Nodules)

Chert (Microcrystalline Quartz, SiO2)

Glauconitic Sandstone

Glauconitic Quartz Arenite

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)

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)

Petrified Wood

Silicified Wood (SiO2)

Chert (Flint)

Microcrystalline or cryptocrystalline quartz (SiO2)

Chert (Iron-rich variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Yellow Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Glauconitic Sandstone

Glauconitic Sandstone (contains (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Petrified Wood

Silicified Wood (primarily Chalcedony or Quartz, SiO2)

Petrified Wood (Calamites Fossil)

Calamites sp. (Silicified/Permineralized Plant Fossil)

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Amber

Succinite (Fossilized Resin C10H16O)

Asphalt / Bituminous Aggregate

Bituminous mixture (Hydrocarbon-based sediment)

Quartz Geode

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)