Rock Identifier

Category

Mineral (Biogenic Replacement)

Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.

Fossil fish specimen (Fossilized fish vertebrate, likely an articulated fish impression; exact taxon indeterminate) — fossil

Fossil fish specimen

Fossilized fish vertebrate, likely an articulated fish impression; exact taxon indeterminate

Weathered fossil shell fragment (Likely a fossilized bivalve or gastropod fragment; exact taxon cannot be determined from one view) — fossil

Weathered fossil shell fragment

Likely a fossilized bivalve or gastropod fragment; exact taxon cannot be determined from one view

Fossil tooth, likely shark tooth (Fossilized selachian tooth; exact species cannot be determined from the image) — fossil

Fossil tooth, likely shark tooth

Fossilized selachian tooth; exact species cannot be determined from the image

Calcite (Calcite (Calcium Carbonate, CaCO3)) — mineral

Calcite

Calcite (Calcium Carbonate, CaCO3)

Chert (Chert (SiO2)) — sedimentary

Chert

Chert (SiO2)

Fossil Coral (Cnidaria Anthozoa (Fossilized)) — sedimentary

Fossil Coral

Cnidaria Anthozoa (Fossilized)

Likely weathered iron-rich breccia or jasper (Silicified iron-oxide breccia; exact identification requires testing) — sedimentary

Likely weathered iron-rich breccia or jasper

Silicified iron-oxide breccia; exact identification requires testing

Fossilized Shark Tooth (Selachimorpha fossil (varies by species)) — fossil

Fossilized Shark Tooth

Selachimorpha fossil (varies by species)

Fossil Shark Tooth (Chondrichthyes (Class)) — fossil

Fossil Shark Tooth

Chondrichthyes (Class)

Fossil oyster shell (Fossilized bivalve shell, likely Ostrea or Crassostrea species; primarily calcite (CaCO₃)) — fossil

Fossil oyster shell

Fossilized bivalve shell, likely Ostrea or Crassostrea species; primarily calcite (CaCO₃)

Fossilized Crinoid Stem Cross-Section (Crinoidea) — fossil

Fossilized Crinoid Stem Cross-Section

Crinoidea

Chert (Chert (Microcrystalline Quartz, SiO2)) — sedimentary

Chert

Chert (Microcrystalline Quartz, SiO2)

Fossilized Gastropod Shell (Class Gastropoda (Fossil)) — sedimentary

Fossilized Gastropod Shell

Class Gastropoda (Fossil)

Jasper (Silicon dioxide (SiO2) with impurities) — sedimentary

Jasper

Silicon dioxide (SiO2) with impurities

Galena with Pyrite on Matrix (Lead(II) sulfide (PbS) with Iron disulfide (FeS2)) — mineral

Galena with Pyrite on Matrix

Lead(II) sulfide (PbS) with Iron disulfide (FeS2)

Tiger's Eye (Silicon Dioxide with Crocidolite (SiO2)) — mineral

Tiger's Eye

Silicon Dioxide with Crocidolite (SiO2)

Pyrite (Iron Sulfide (FeS2)) — mineral

Pyrite

Iron Sulfide (FeS2)

Green Fluorite (Fluorite (Calcium Fluoride, CaF2)) — mineral

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Limonite-stained ironstone, possibly goethite (Goethite/limonite (FeO(OH) and hydrated iron oxides), identification tentative) — mineral

Limonite-stained ironstone, possibly goethite

Goethite/limonite (FeO(OH) and hydrated iron oxides), identification tentative

Rhodochrosite (Manganese Carbonate (MnCO3)) — mineral

Rhodochrosite

Manganese Carbonate (MnCO3)

Hematite Nodular Iron Ore (Hematite (Fe2O3)) — mineral

Hematite Nodular Iron Ore

Hematite (Fe2O3)

Chalcedony (Grey/White Agate) (Silicon Dioxide (SiO₂)) — mineral

Chalcedony (Grey/White Agate)

Silicon Dioxide (SiO₂)

Pyrite (Iron Sulfide (FeS2)) — mineral

Pyrite

Iron Sulfide (FeS2)

Likely fossil oyster shell (Fossilized bivalve shell; exact species cannot be identified from the image) — fossil

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

Red Jasper (Chert) (Silicon Dioxide (SiO2) with iron oxide inclusions) — sedimentary

Red Jasper (Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Red Jasper (Jasper (Silicon Dioxide, SiO2)) — sedimentary

Red Jasper

Jasper (Silicon Dioxide, SiO2)

Megalodon Shark Tooth (Otodus megalodon) — fossil

Megalodon Shark Tooth

Otodus megalodon

Brachiopod Fossil in Limestone (Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)) — sedimentary

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Rhodonite (Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3) — mineral

Rhodonite

Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3

Ammonite fossil (Ammonoidea; likely a polished small ammonite, possibly Cleoniceras) — fossil

Ammonite fossil

Ammonoidea; likely a polished small ammonite, possibly Cleoniceras

Shark Tooth Fossil (Chondrichthyes fossil) — fossil

Shark Tooth Fossil

Chondrichthyes fossil

Iron-stained fossiliferous rock, possibly fossil wood (Likely silicified/petrified wood in iron-rich silica matrix; exact identification requires microscopy) — fossil

Iron-stained fossiliferous rock, possibly fossil wood

Likely silicified/petrified wood in iron-rich silica matrix; exact identification requires microscopy

Green fluorite (rough specimen) (Fluorite, calcium fluoride (CaF₂)) — mineral

Green fluorite (rough specimen)

Fluorite, calcium fluoride (CaF₂)

Quartz (Chert/Chalcedony variety) (Silicon Dioxide (SiO2)) — mineral

Quartz (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Pyrite (Iron Sulfide (FeS2)) — mineral

Pyrite

Iron Sulfide (FeS2)

Hematite with Magnetite (Iron Oxide (Fe2O3)) — mineral

Hematite with Magnetite

Iron Oxide (Fe2O3)

Fossil coral pebble (Fossilized colonial coral, commonly Favosites or Hexagonaria) — fossil

Fossil coral pebble

Fossilized colonial coral, commonly Favosites or Hexagonaria

Fossiliferous Limestone / Petrifaction (Sedimentary rock with fossil inclusions / Calcium Carbonate (CaCO3)) — fossil

Fossiliferous Limestone / Petrifaction

Sedimentary rock with fossil inclusions / Calcium Carbonate (CaCO3)

Jasper (Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)) — sedimentary

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Polished fossil-bearing limestone (Fossiliferous micritic limestone, likely containing gastropod or ammonoid fragments) — fossil

Polished fossil-bearing limestone

Fossiliferous micritic limestone, likely containing gastropod or ammonoid fragments

Likely brown jasper or iron-stained chert (Microcrystalline quartz (SiO₂), with iron-oxide inclusions) — mineral

Likely brown jasper or iron-stained chert

Microcrystalline quartz (SiO₂), with iron-oxide inclusions

Tiger's Eye (Tiger's eye (Pseudomorph of Quartz after Crocidolite), SiO2) — metamorphic

Tiger's Eye

Tiger's eye (Pseudomorph of Quartz after Crocidolite), SiO2