Sandstone (with Lichen)
Arenite (composed primarily of SiO2)
sedimentary
Category
Mineral Like Biological Tissue
Browse mineral like biological tissue specimens identified by the Rock Identifier community.
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Natural Pearl
Calcium carbonate (primarily Aragonite and Conchiolin), CaCO3
mineral
Sandstone concretion (Ironstone-stained)
Arenite with Limonite/Hematite staining (Silica-based with Iron Oxides)
sedimentary
Pyrite
Iron Sulfide (FeS2)
mineral
Petrified Wood
Silicified wood (primarily quartz, SiO2)
sedimentary
Fossilized Shark Tooth
Chondrichthyes (Class)
fossil
Pearl
Calcium Carbonate (CaCO3) in the form of Aragonite
mineral
Brachiopod Fossil
Phylum Brachiopoda (likely Order Rhynchonellida or Spiriferida)
fossil
Petrified wood
Silicified wood; commonly quartz (SiO₂) replacing wood tissue
fossil
Chert
Chert (SiO2)
sedimentary
Pearl
Aragonite (CaCO3) with Conchiolin
mineral
Amber
Succinite (fossilized tree resin)
fossil
Leopard-skin jasper (likely orbicular jasper)
Silicified volcanic rock, primarily microcrystalline quartz (SiO₂) with iron-oxide and dark mineral inclusions
metamorphic
Shark Tooth Fossil
Otodus sp. (possibly Cretalamna)
fossil
Rough Amber (likely Copal or immature Amber)
Organic gemstone / Succinite (if Baltic)
mineral
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Calcite
Calcium Carbonate (CaCO3)
mineral
Amber
Succinite (fossilized resin)
mineral
Megalodon Shark Tooth Fossil
Otodus megalodon (fossilized in sedimentary matrix)
sedimentary
Coral Fossil (Scleractinia)
Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)
sedimentary
Selenite desert rose
Gypsum (CaSO₄·2H₂O), rosette habit
mineral
Pearl
Calcium Carbonate (primarily Aragonite and Calcite), CaCO3
mineral
Precious Red Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
Mineral (Organic Gemstone)
Calcite
Calcium Carbonate (CaCO3)
mineral
Fossilized coral or stromatoporoid
Calcareous coral, likely an indeterminate fossil colonial coral (phylum Cnidaria)
fossil
Fossilized wood or plant fragment
Petrified wood (silicified fossil wood; commonly Araucarioxylon or related taxa)
fossil
Amber
Succinite (C10H16O)
mineraloid
Fossil crinoid stem segment (columnal)
Crinoidea; commonly preserved as calcite ossicles, often called entrocrinite
fossil
Amber
Succinite
mineraloid
Likely tumbled yellow calcite or aragonite
Calcite (CaCO₃) or aragonite (CaCO₃)
mineral
Polished petrified wood
Silicified wood; commonly quartz/chalcedony (SiO₂) replacing wood tissue
fossil
Pyrite
Iron Disulfide (FeS2)
mineral
Petrified wood
Silicified wood, commonly quartz (SiO₂) replacing woody tissue
fossil
Fossilized shell or small fossil fragment
Indeterminate fossil; possibly a partial gastropod or bivalve, mineralized with calcite
fossil
Piddock bored rock (likely Mudstone or Shale)
Ichnofossil (Gastrochaenolites borings) in Fine-grained Sedimentary Rock
sedimentary
Calcite
Calcium Carbonate (CaCO3)
mineral
Aragonite (Star Cluster or Twinned variety)
Aragonite (Calcium Carbonate, CaCO3)
mineral
Tonsil Stone (Tonsillolith)
Calcium phosphate / Calcium carbonate biomineral
mineral
Chert Nodule (Fossiliferous Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Polished fossil tooth, likely shark tooth
Likely fossilized shark tooth; exact taxon cannot be determined from this image
fossil
Brachiopod Fossil in Limestone
Phylum Brachiopoda embedded in sedimentary rock
fossil
Ironstone Concretion (Limonite/Goethite)
Goethite/Limonite concretion (FeO(OH)·nH2O)
sedimentary