Sedimentary (Biogenic Sediment Or Biological Remain)

Polished petrified wood

Silicified wood; commonly quartz/chalcedony (SiO₂) replacing cellular tissue

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite

Fossil tooth

Mineralized vertebrate tooth; exact animal and species cannot be determined from the image

Coral Fossil (Scleractinia)

Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)

Fossiliferous Limestone (Crinoidal)

Bioclastic Limestone (predominantly CaCO3)

Pyrite

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Fossilized bivalve shell

Bivalvia (likely a venerid or similar clam); shell composed mainly of CaCO₃ as aragonite/calcite

Chert (with potential fossil inclusion)

Microcrystalline Quartz (SiO2)

Sandstone (Weathered Cobble)

Clastic sedimentary rock (primarily SiO2)

Coquina

Biogenic Limestone (Calcite/Aragonite base, CaCO3)

Botryoidal hematite (iron-oxide specimen)

Hematite, Fe₂O₃; possibly mixed with goethite/limonite

Chert (Greenish-Grey variety)

Microcrystalline quartz (SiO2)

Chert (variant Flint/Novaculite)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossil oyster shell

Ostrea or Exogyra sp. (identification uncertain)

Chert (or Jasper)

Microcrystalline Quartz (SiO2)

Pyrite

Iron Sulfide (FeS2)

Fossil-bearing limestone pebble

Fossiliferous limestone, chiefly calcite (CaCO₃); the visible fossil cannot be identified confidently from the image

Likely fossiliferous limestone fragment

Calcareous fossil assemblage, chiefly calcium carbonate (CaCO₃), possibly crinoid, bivalve, or bryozoan material in limestone

Blue Apatite

Fluoroapatite (Ca5(PO4)3F)

Limonite Geode (Ironstone Concretion)

Goethite/Limonite FeO(OH)·nH2O

Pyrite

Iron Sulfide (FeS2)

Calcite

Calcium Carbonate (CaCO3)

Pyrite

Iron Disulfide (FeS2)

Limestone (Decorative Gravel)

Calcium Carbonate (CaCO3)

Oyster Shell (Biogenic Calcium Carbonate)

Crassostrea virginica (or related species) - Calcium Carbonate (CaCO3)

Fossiliferous Limestone

CaCO3 (principally Calcite or Aragonite)

Chert (with Limestone/Dolomite host)

Microcrystalline Quartz (SiO2)

Banded Jasper

Silicon Dioxide (SiO2) with impurities

Limestone with Fossil Inclusion

Calcium Carbonate (CaCO3) - Bioclastic Limestone

Fossil coral limestone

Fossilized colonial coral, commonly tabulate or rugose coral in calcite-rich limestone (CaCO₃)

Weathered iron-stained quartzite or jasper

Quartzite dominated by quartz (SiO₂), with iron oxides/hydroxides such as hematite and limonite

Piddock-bored Mudstone

Lutite (Siltstone or Mudstone) with Pholad borings

Chert Pebble with Quartz Veining

Microcrystalline Quartz (SiO2)

Limonite (Hydrated Iron Oxide / Bog Iron)

FeO(OH)·nH2O

Weathered vesicular volcanic rock, likely basaltic scoria

Vesicular basalt/scoria; chiefly plagioclase, pyroxene, olivine, and volcanic glass

Trace Fossil (Lichenandites or Rhynie Chert Chert with Microfossils)

Trace fossil in microcrystalline quartz (SiO2)

Megalodon Shark Tooth Fossil

Otodus megalodon

Chert (Chert breccia)

SiO2 (Silicon Dioxide)

Likely calcite or limestone fragment

Calcite (CaCO₃), possibly limestone dominated by calcite

Aragonite Star Cluster

Aragonite (Calcium Carbonate, CaCO3)

Pyrite (Iron Pyrites)

Iron Sulfide (FeS2)