Rock Identifier

Category

Mineral (Biogenic Replacement)

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

Magnetite (Magnetite (Fe3O4)) — mineral

Magnetite

Magnetite (Fe3O4)

Note: Image shows a biological specimen (Rat), not a rock. Representative geological equivalent: Galena (due to lead-grey colors in fur). (Galena (PbS)) — mineral

Note: Image shows a biological specimen (Rat), not a rock. Representative geological equivalent: Galena (due to lead-grey colors in fur).

Galena (PbS)

Weathered quartz-rich rock, likely silicified limestone or quartzite (Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃) and iron-oxide staining) — metamorphic

Weathered quartz-rich rock, likely silicified limestone or quartzite

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃) and iron-oxide staining

Chert (Flint) with Limonite Staining (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Flint) with Limonite Staining

Microcrystalline Quartz (SiO2)

Chert / Jasper (Silicon Dioxide (SiO2)) — sedimentary

Chert / Jasper

Silicon Dioxide (SiO2)

Red Jasper (Silicon Dioxide (SiO2) with Hematite inclusions) — sedimentary

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Fossilized Shark Tooth (Chondrichthyes (Class) fossilized tooth) — fossil

Fossilized Shark Tooth

Chondrichthyes (Class) fossilized tooth

Tiger's Eye (Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)) — mineral

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)

Flint (Sedimentary cryptocrystalline quartz (SiO2)) — sedimentary

Flint

Sedimentary cryptocrystalline quartz (SiO2)

N/A - Image is non-geological (Acrylonitrile Butadiene Styrene (ABS) or Polypropylene (PP)) — Synthetic material (Plastic/Polymer)

N/A - Image is non-geological

Acrylonitrile Butadiene Styrene (ABS) or Polypropylene (PP)

Synthetic material (Plastic/Polymer)

Calcite (likely a tumbled specimen) (Calcite (CaCO
3
)) — Mineral

Calcite (likely a tumbled specimen)

Calcite (CaCO 3 )

Yellow Jasper (Jasper (Silicon Dioxide with Iron Oxide inclusions), SiO2) — sedimentary

Yellow Jasper

Jasper (Silicon Dioxide with Iron Oxide inclusions), SiO2

Chert Nodule in Limestone (Chert (Microcrystalline Quartz, SiO2) and Limestone (Calcium Carbonate, CaCO3)) — sedimentary

Chert Nodule in Limestone

Chert (Microcrystalline Quartz, SiO2) and Limestone (Calcium Carbonate, CaCO3)

Fossil Coral (Hexagonaria or similar rugose/tabulate coral fossil (Calcium Carbonate, CaCO3)) — fossil

Fossil Coral

Hexagonaria or similar rugose/tabulate coral fossil (Calcium Carbonate, CaCO3)

Chert (Common Opal/Agate inclusion) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Common Opal/Agate inclusion)

Microcrystalline Quartz (SiO2)

Bismuth (Bismuth (Bi)) — mineral

Bismuth

Bismuth (Bi)

Fossil Coral (Rugosa or Tabulata / Hexacorallia (replaced with silica or calcite)) — fossil

Fossil Coral

Rugosa or Tabulata / Hexacorallia (replaced with silica or calcite)

Mammoth Molar Fossil (Mammuthus primigenius (Tooth fragment)) — fossil

Mammoth Molar Fossil

Mammuthus primigenius (Tooth fragment)

Magnetite-rich Iron Ore (Magnetite (Fe3O4)) — mineral

Magnetite-rich Iron Ore

Magnetite (Fe3O4)

Celestine (or Celestite) (Strontium sulfate (SrSO4)) — mineral

Celestine (or Celestite)

Strontium sulfate (SrSO4)

Celestite (Celestine) (Strontium sulfate (SrSO4)) — mineral

Celestite (Celestine)

Strontium sulfate (SrSO4)

Fossilized Bone Fragment (Permineralized Skeletal Element (Likely Vertebrate)) — sedimentary

Fossilized Bone Fragment

Permineralized Skeletal Element (Likely Vertebrate)

Possible flint or slag fragment (Microcrystalline quartz (chalcedony), or iron-rich industrial slag) — mineral

Possible flint or slag fragment

Microcrystalline quartz (chalcedony), or iron-rich industrial slag

Galena (Lead(II) sulfide (PbS)) — mineral

Galena

Lead(II) sulfide (PbS)

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Chert (or Jasper) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (or Jasper)

Microcrystalline Quartz (SiO2)

Fossilized Bone (Petrified Bone) (Permineralized Bone Fossil) — fossil

Fossilized Bone (Petrified Bone)

Permineralized Bone Fossil

Galena (Lead(II) sulfide (PbS)) — mineral

Galena

Lead(II) sulfide (PbS)

Chert (Microcrystalline Quartz (SiO2)) — sedimentary

Chert

Microcrystalline Quartz (SiO2)

Ammonite Fossil (Ammonoidea (subclass)) — sedimentary

Ammonite Fossil

Ammonoidea (subclass)

Pyrite (on Quartz/Host Rock) (Iron Sulfide (FeS₂)) — mineral

Pyrite (on Quartz/Host Rock)

Iron Sulfide (FeS₂)

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

Chert

Chert (Microcrystalline Quartz, SiO2)

Hematite (Botryoidal/Kidney Ore) (Iron(III) oxide (Fe2O3)) — mineral

Hematite (Botryoidal/Kidney Ore)

Iron(III) oxide (Fe2O3)

Chalcedony Nodule (Commonly known as Agate or Chert) (Microcrystalline Quartz (SiO2)) — mineral

Chalcedony Nodule (Commonly known as Agate or Chert)

Microcrystalline Quartz (SiO2)

Chert (varietal Jasper or Mudstone Flint) (Silicon dioxide (SiO2) with impurities) — sedimentary

Chert (varietal Jasper or Mudstone Flint)

Silicon dioxide (SiO2) with impurities

Jasper (Silicon dioxide (SiO2) with iron oxide inclusions) — sedimentary

Jasper

Silicon dioxide (SiO2) with iron oxide inclusions

Bivalve Fossil (Clam) (Class Bivalvia (Mollusca)) — fossil

Bivalve Fossil (Clam)

Class Bivalvia (Mollusca)

Chert Geode or Nodule (Microcrystalline Quartz (SiO2)) — sedimentary

Chert Geode or Nodule

Microcrystalline Quartz (SiO2)

Flint (Silicon Dioxide (SiO2) - variety of Chert) — sedimentary

Flint

Silicon Dioxide (SiO2) - variety of Chert

Fossil Shell (Bivalve) (Class Bivalvia (Likely a member of the Ostreidae or Gryphaeidae family), CaCO3) — sedimentary

Fossil Shell (Bivalve)

Class Bivalvia (Likely a member of the Ostreidae or Gryphaeidae family), CaCO3

Fossilized Coral (Favosites) (Favosites (extinct genus of tabulate coral)) — sedimentary

Fossilized Coral (Favosites)

Favosites (extinct genus of tabulate coral)

Flint (SiO2 (Microcrystalline Quartz / Chert)) — sedimentary

Flint

SiO2 (Microcrystalline Quartz / Chert)