Stromatolite
Biogenic Sedimentary Rock (composed predominantly of CaCO3)
sedimentary
Category
Mineral (Biogenic)
Browse mineral (biogenic) specimens identified by the Rock Identifier community.
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Fossiliferous Limestone with Crinoid stems
Calcite-rich Biogenic Sedimentary Rock (CaCO3)
sedimentary
Fossiliferous Limestone
Limestone with fossil inclusions (CaCO3)
sedimentary
Fossiliferous Limestone
Limestone (CaCO3) with Crinoid/Bivalve fossils
sedimentary
Chert / Flint
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Flint (Chert Nodules)
SiO2 (Cryptocrystalline Quartz)
sedimentary
Black Pearl (Tahitian Type)
Aragonite / Conchiolin composite (CaCO3)
mineraloid
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with marine fossils
fossil
Limestone (Fossiliferous)
Sedimentary Carbonate Rock (CaCO3)
sedimentary
Queen Conch Shell (Biogenic Calcium Carbonate)
Aliger gigas (synonym Strombus gigas); Composition: Aragonite (CaCO3)
mineral
Polished brown flint/chert (likely)
Microcrystalline quartz, SiO₂ (chalcedonic flint/chert)
sedimentary
Pale limestone or calcite-rich rock
Calcite (CaCO₃), likely micritic limestone
sedimentary
Chert or flint fragment
Microcrystalline quartz (SiO₂), likely chert/flint
sedimentary
Chert or flint fragment
Microcrystalline quartz (SiO₂), commonly chalcedony with cryptocrystalline quartz
sedimentary
Chert or flint fragment
Microcrystalline quartz (SiO₂), often with chalcedony
sedimentary
Chert (Flint Nodule)
Microcrystalline Quartz (SiO2)
sedimentary
Banded Chert Pebble
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (often called Flint)
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Flint (chert) with chalcedony/quartz
Microcrystalline quartz, SiO₂; likely flint or siliceous chert with a chalcedonic edge
sedimentary
Staghorn Coral Specimen
Acropora cervicornis (Calcium Carbonate, CaCO3)
sedimentary
Red Coral (Precious Coral)
Corallium rubrum (Calcium Carbonate, CaCO3)
gemstone
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Jasper / Flint)
Microcrystalline Quartz (SiO2) with Iron Oxides
sedimentary
Likely weathered gray flint/chert pebble
Microcrystalline quartz (SiO₂), commonly with chalcedony and minor impurities
sedimentary
Chert (Nodular Chert)
Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)
sedimentary
Chert (Flint) / Silicified Limestone
Microcrystalline Quartz (SiO2)
sedimentary
Crinoid Fossil Marble
Crinoidal Limestone / Phylum Echinodermata
sedimentary
Limestone with possible fossil inclusions
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Shell Cameo
Cypraecassis rufa (Bullmouth Queen Helmet Shell)
mineraloid / biogenic specimen
Flint or chert fragment
Microcrystalline quartz (SiO₂), likely flint/chert
sedimentary
Calcite-rich limestone (possibly fossiliferous limestone)
Calcite, CaCO₃, in a limestone matrix
sedimentary
Chert (Flint)
Microcrystalline or cryptocrystalline quartz (SiO2)
sedimentary
Chert (and Flint variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert / Flint (with Jasper inclusions)
Microcrystalline Quartz (SiO2)
sedimentary
Banded chert or siliceous mudstone
Microcrystalline quartz (chalcedony), SiO₂; possibly ferruginous shale
sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
sedimentary
Operculum shell (often called "Shiva's Eye" or "Cat's Eye")
Operculum of a gastropod (e.g., Turbinidae family), primarily Calcium Carbonate (CaCO3) in the form of aragonite.
fossil
Fossiliferous Limestone (with Rugose Coral)
Limestone with Tetracoralla (Rugosa) fossil
fossil
Fossiliferous Limestone (Coquina / Shell Limestone Egg)
Biogenic Limestone (composed primarily of Calcite, CaCO3)
sedimentary
Pearl (in Marcasite Jewelry)
Biogenic Calcium Carbonate (primarily Aragonite, CaCO3)
gemstone
Beach Pebbles and Quartz Aggregates
Quartz pebbles and biogenic fragments (SiO2, CaCO3)
sedimentary