Fossilized shell fragment
Bioclastic carbonate, likely a bivalve or brachiopod shell preserved as calcite/aragonite
fossil
Category
Mineral (Biogenic Replacement)
Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.
Polished fossil shark tooth
Likely fossilized shark tooth, possibly Otodus obliquus or a related lamniform shark
fossil
Chert (Jasper variety)
Silicon dioxide (SiO2)
sedimentary
Fossilized Shark Teeth
Carcharhiniformes or Lamniformes species (common mineral: Fluorapatite/Ca5(PO4)3F)
sedimentary (fossilized organic matter)
Brachiopod Fossil in Matrix
Phylum Brachiopoda
fossil
Fossilized coral or silicified organic limestone
Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination
fossil
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
mineral
Small shell fragment (likely gastropod or bivalve fossil)
Fossilized calcium-carbonate shell; chiefly aragonite or calcite (CaCO₃)
fossil
Tiger's Eye (Rough)
Pseudomorph of Quartz after Crocidolite (SiO2 with FeOOH inclusions)
metamorphic
Tiger's Eye (with Blue Tiger's Eye / Hawk's Eye)
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions)
metamorphic
Fossil Bone Fragment
Petrified bone (permineralized hydroxyapatite)
fossil
Otodus Shark Tooth
Otodus obliquus
fossil
Shark Tooth Fossil
Elasmobranchii dentition (fossilized)
fossil
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Rhodonite
Manganese Silicate (Mn,Fe,Mg,Ca)SiO3
mineral
Fossilized bivalve shell fragment
Fossil Mollusca, likely a bivalve (class Bivalvia); exact genus cannot be determined from the image
fossil
Fossil Shark Tooth
Chondrichthyes (Class)
fossil
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Pyrite
Iron Sulfide (FeS2)
mineral
Polished fossil ammonite
Ammonite cephalopod fossil, likely an ammonite mold/cast in calcite or aragonite-derived mineralization
fossil
Quartz (Jasper / Chert)
Silicon Dioxide (SiO2)
sedimentary
Tumbled brown jasper
Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and clay inclusions
mineral
Polished ocean jasper (orbicular jasper)
Microcrystalline quartz/chalcedony (SiO₂) with iron-oxide and other mineral inclusions
mineral
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Fossil Shell
Invertebrate fossil (Mollusca)
fossil
Petoskey Stone
Hexagonaria percarinata
fossil
Bivalve Fossil (Clam Fossil)
Class Bivalvia (likely Gryphaea or similar Order)
fossil
Chert (Chalcedony/Agate variety)
Silicon Dioxide (SiO2)
sedimentary
Chrysanthemum Stone
Chrysanthemum Stone (Calcite/Celestite/Strontianite in Limestone)
sedimentary
Chert (Flint) with Glauconite
Microcrystalline Quartz (SiO2)
sedimentary
Rainbow Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Unakite Epidote-Granite
Unakite (Epidotized Granite)
metamorphic
Chert (with potential fossil inclusion)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Gastropod Shell
Gastropoda (Class) replacement / internal cast (steinkern)
fossil
Fossilized Bone Chunk
Permineralized Vertebrate Bone (indeterminant)
fossil
Possible fossil tooth or bone fragment
Indeterminate fossilized vertebrate material; species cannot be identified reliably from this image
fossil
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Agate variety)
Silicon Dioxide (SiO2)
sedimentary
Fossilized shark tooth
Fossil shark tooth; exact shark species cannot be determined from this image
fossil
Fossil Shark Tooth
Chondrichthyes (class)
fossil
Shark Tooth Fossil
Otodus obliquus (or similar prehistoric lamniform shark tooth)
fossil
Gastropod Fossil (Snail Internal Mold)
Gastropoda; internal mold (steinkern), often composed of Calcium Carbonate (CaCO3) or Silica (SiO2)
sedimentary