Organic Gemstone (Fossilized Resin)

Dragon Stone

Ohko Stone (Argillaceous sedimentary rock)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Fossilized Sand Tiger Shark Tooth

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

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (SiO2)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Fossilized Shell in Limestone

Bivalve fossil (CaCO3) in Carbonate Sedimentary Rock

Ammolite

Biogenic gemstone (Aragonite, CaCO3)

Petoskey Stone

Hexagonaria percarinata (Fossilized Coral)

Fossil Shell (Bivalve)

Phylum Mollusca, Class Bivalvia (typically composed of Calcium Carbonate / CaCO3)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Ammolite

Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)

Fossilized Pycnodonte Oyster

Pycnodonte (Gryphaeostrea) species; Composition is Calcium Carbonate (Calcite/Aragonite)

Fossilized Shark Tooth

Carcharodon carcharias (fossilized) / Hydroxyapatite permineralized with silica or iron

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Travertine

Calcareous Tufa (CaCO3)

Fossil Shark Tooth

Carcharodon or Carcharias fossil (Vertebrate Fossil)

Chert / Flint (with Crinoid Stem Molds)

Microcrystalline Quartz (SiO2)

Kambaba Jasper

Stromatolite (Fossilized Algae)

Tiger's Eye

Titanium-containing Quartz (Silica: SiO2)

Glauconitic Sandstone (Greensand pebble)

Glauconitic Quartz Sandstone (K(Fe,Al)2(Si,Al)4O10(OH)2)

Turquoise (Dyed Howlite or Magnesite imitation)

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

Fossilized Megalodon Tooth Fragment

Otodus megalodon (Carcharocles megalodon fossil)

Fossilized Bone Fragment

Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)

Chert (and Fossilized Brachiopod shell)

Sedimentary Cryptocrystalline Quartz (SiO2)

Montana Moss Agate

Chalcedony (Silicon Dioxide, SiO2)

Fossilized Shark Tooth

Scapanorhynchus (Sand Tiger Shark relative)

Turquoise (likely stabilized or Howlite/Magnesite imitation)

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

Jasper

Silicon dioxide (SiO2)

Dendritic Opal

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

Fossil Coral (Rugose Coral Fragment)

Rugosa (extinct order of solitary and colonial corals)

Fossilized Shark Tooth (Basal Bone)

Otodus sp. (Mineralized Hydroxyapatite)

Dendritic Opal (Merlinite)

Hydrated Silica with Manganese/Iron oxide inclusions (SiO2·nH2O)

Stromatolite (Jasper-replaced)

Fossilized Stromatolite (Cyanobacteria / Cryptozon / Silica SiO2)

Chert (Chert Nodule with Cortex)

Microcrystalline Quartz (SiO2)

Knightia Fossil in Limestone

Knightia eocaena in micritic limestone

Fossil Coral (Honeycomb Coral)

Favosites (extinct genus of Tabulate coral)

Pearl (in a decorative hair comb setting)

Calcium carbonate (CaCO3) primarily as Aragonite, bonded with Conchiolin

Crinoid Stem Fragment

Crinoid (Phylum Echinodermata, Class Crinoidea)

Mookaite Jasper

Silicified Radiolarite (SiO2)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)