Rock Identifier

Category

Mineral (Biogenic Replacement)

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

Fossilized coral or bryozoan limestone (Calcitic fossiliferous limestone; likely colonial coral/bryozoan fragments, CaCO₃) — fossil

Fossilized coral or bryozoan limestone

Calcitic fossiliferous limestone; likely colonial coral/bryozoan fragments, CaCO₃

fossil
Fossilized colonial coral (Tabulate coral, likely Favosites or a related genus) — fossil

Fossilized colonial coral

Tabulate coral, likely Favosites or a related genus

fossil
Jasper (Brown Iron-Rich Variety) (Silicon Dioxide (SiO2) with Fe2O3 (Iron Oxide/Crystalline Quartz)) — sedimentary

Jasper (Brown Iron-Rich Variety)

Silicon Dioxide (SiO2) with Fe2O3 (Iron Oxide/Crystalline Quartz)

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

Banded Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

sedimentary
Fossilized bivalve shell in limestone (Calcitic fossil shell; likely an oyster or other rudist/bivalve (Bivalvia), preserved in carbonate rock) — fossil

Fossilized bivalve shell in limestone

Calcitic fossil shell; likely an oyster or other rudist/bivalve (Bivalvia), preserved in carbonate rock

fossil
Fossil Belemnite Guard (Belemnitella spp. (rostrum)) — fossil

Fossil Belemnite Guard

Belemnitella spp. (rostrum)

fossil
Polished fossil coral (likely fossilized honeycomb or tabulate coral) (Fossilized tabulate coral; commonly Favosites or related genera, preserved mainly as calcite (CaCO₃)) — fossil

Polished fossil coral (likely fossilized honeycomb or tabulate coral)

Fossilized tabulate coral; commonly Favosites or related genera, preserved mainly as calcite (CaCO₃)

fossil
Chert (Jasper/Agate variety) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

sedimentary
Goniatite Fossil (Order Goniatitida) — fossil

Goniatite Fossil

Order Goniatitida

fossil
Chert (Jasper/Limonitic Chert) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Jasper/Limonitic Chert)

Microcrystalline Quartz (SiO2)

sedimentary
Fossiliferous Chert with Brachiopod Impression (Chert (SiO2) containing Brachiopoda fossil remains) — sedimentary

Fossiliferous Chert with Brachiopod Impression

Chert (SiO2) containing Brachiopoda fossil remains

sedimentary
Galena-bearing sulfide ore (Galena (PbS), likely with sphalerite, pyrite, and/or iron-oxide matrix) — mineral

Galena-bearing sulfide ore

Galena (PbS), likely with sphalerite, pyrite, and/or iron-oxide matrix

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

Hematite (Iron Ore)

Hematite (Fe2O3)

mineral
Fossil fish slab (Fossilized fish remains, likely a laminated shale-hosted vertebrate fossil; exact taxon is indeterminate from the image) — fossil

Fossil fish slab

Fossilized fish remains, likely a laminated shale-hosted vertebrate fossil; exact taxon is indeterminate from the image

fossil
Galena (Galena (lead sulfide, PbS)) — mineral

Galena

Galena (lead sulfide, PbS)

mineral
Specular Hematite and Magnetite Ore (Iron Oxide (Fe2O3 and Fe3O4)) — mineral

Specular Hematite and Magnetite Ore

Iron Oxide (Fe2O3 and Fe3O4)

mineral
Tiger's Eye (SiO2 (Silicon Dioxide with inclusions of Goethite/Limonite)) — Metamorphic

Tiger's Eye

SiO2 (Silicon Dioxide with inclusions of Goethite/Limonite)

Metamorphic
Synthetic Sapphire and Ion-X Glass (Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass) — mineral

Synthetic Sapphire and Ion-X Glass

Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass

mineral
Chert (often called Jasper or Flint) (Microcrystalline Silica (SiO2)) — sedimentary

Chert (often called Jasper or Flint)

Microcrystalline Silica (SiO2)

sedimentary
Chert Arrowhead (Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert Arrowhead

Cryptocrystalline Quartz (SiO2)

sedimentary
Sea Shell (Fighting Conch Fragment) (Calcium Carbonate (CaCO3) - Strombus alatus fragment) — sedimentary (biogenic)

Sea Shell (Fighting Conch Fragment)

Calcium Carbonate (CaCO3) - Strombus alatus fragment

sedimentary (biogenic)
Milky Quartz (Silicon Dioxide (SiO2)) — mineral

Milky Quartz

Silicon Dioxide (SiO2)

mineral
Petrified Wood (Silicified Wood / Fossilized Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood / Fossilized Wood (SiO2)

sedimentary
Fossilized bone fragment (Mineral-replaced vertebrate bone, commonly apatite [Ca₅(PO₄)₃(F,OH,Cl)]) — fossil

Fossilized bone fragment

Mineral-replaced vertebrate bone, commonly apatite [Ca₅(PO₄)₃(F,OH,Cl)]

fossil
Fossilized bone fragment, possibly mammalian long bone (Mineralized bone (commonly apatite, Ca₅(PO₄)₃(OH,F,Cl), replacing original bone)) — fossil

Fossilized bone fragment, possibly mammalian long bone

Mineralized bone (commonly apatite, Ca₅(PO₄)₃(OH,F,Cl), replacing original bone)

fossil
Fossil Coral (Rugosa or Tabulata coral fossil) — fossil

Fossil Coral

Rugosa or Tabulata coral fossil

fossil
Chert (specifically Flint or Jasperoid) (Silicon Dioxide (SiO2)) — sedimentary

Chert (specifically Flint or Jasperoid)

Silicon Dioxide (SiO2)

sedimentary
Fossilized Echinoid (Sea Urchin) (Echinoidea (Fossil)) — sedimentary

Fossilized Echinoid (Sea Urchin)

Echinoidea (Fossil)

sedimentary
Metallic sulfide ore, likely galena-bearing rock (Galena (lead sulfide, PbS), possibly with pyrite or other sulfides) — mineral

Metallic sulfide ore, likely galena-bearing rock

Galena (lead sulfide, PbS), possibly with pyrite or other sulfides

mineral
Chert (Common Opal/Agatized Rock) (Microcrystalline Quartz (SiO2) with potential Chalcedony/Opaline silica) — sedimentary

Chert (Common Opal/Agatized Rock)

Microcrystalline Quartz (SiO2) with potential Chalcedony/Opaline silica

sedimentary
Galena (likely) (Galena, lead sulfide (PbS)) — mineral

Galena (likely)

Galena, lead sulfide (PbS)

mineral
Galena (Galena (lead sulfide, PbS)) — mineral

Galena

Galena (lead sulfide, PbS)

mineral
Raw galena specimen (Galena (lead sulfide, PbS)) — mineral

Raw galena specimen

Galena (lead sulfide, PbS)

mineral
Quartz (likely Chalcedony or Chert) (Silicon Dioxide (SiO2)) — mineral

Quartz (likely Chalcedony or Chert)

Silicon Dioxide (SiO2)

mineral
Calcite (Calcite (CaCO₃)) — Mineral

Calcite

Calcite (CaCO₃)

Mineral
Tiger's Eye (Pseudomorph of Quartz after Crocidolite (SiO2)) — mineral

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

mineral
Bismuth (Bismuth (Bi)) — mineral

Bismuth

Bismuth (Bi)

mineral
Fossilized coral fragment (Agatized or silicified coral, likely *Hexagonaria* (identification uncertain from photo)) — fossil

Fossilized coral fragment

Agatized or silicified coral, likely *Hexagonaria* (identification uncertain from photo)

fossil
Pyrite (Fool's Gold) (Iron Sulfide (FeS2)) — mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

mineral
Chert (Flint) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

sedimentary
Fossilized Bone (Petrified Bone) (Permineralized Vertebrate Remains) — sedimentary

Fossilized Bone (Petrified Bone)

Permineralized Vertebrate Remains

sedimentary
Fossilized Shark Teeth (Otodus sp. (Eocene Sand Tiger/Mackerel Shark)) — fossil

Fossilized Shark Teeth

Otodus sp. (Eocene Sand Tiger/Mackerel Shark)

fossil