Weathered iron-rich rock fragment
Likely limonite/goethite-bearing ferruginous rock; exact identification requires testing
mineral
Category
Mineral (Biogenic Replacement)
Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.
Chalcedony (Common Agate)
Silicon Dioxide (SiO2)
mineral
Celestine (Celestite)
Celestine (Strontium Sulfate, SrSO4)
mineral
Polished tiger’s eye
Quartz (microcrystalline SiO₂) with crocidolite-derived iron oxides
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Rhodonite
Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3
mineral
Jasper
Silicon dioxide, SiO2
Mineral
Tumbled blue fluorite (likely)
Fluorite, calcium fluoride (CaF₂)
mineral
Blue fluorite
Fluorite (calcium fluoride, CaF₂)
mineral
Iron-rich botryoidal limonite/goethite specimen
Limonite (amorphous hydrated iron oxides, chiefly goethite, α-FeO(OH))
mineral
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Coral
Rugosa / Tabulata coral fossils replaced by silica (Chalcedony/Quartz)
fossil
Fossiliferous shale or mudstone with plant fossils
Carbonaceous mudstone/shale containing fossilized foliage, likely fern or seed-fern impressions
fossil
Chert with Druzy Quartz and Mossy/Iron Inclusions
Microcrystalline Quartz (SiO2)
sedimentary
Weathered quartz-rich rock, likely chert or quartzite
Quartzite/chert; predominantly microcrystalline quartz (SiO₂), with iron-oxide staining and possible minor feldspar or clay minerals
metamorphic
Polished ammonite fossil pendant
Ammonite; likely a polished, mineral-replaced ammonoid shell (commonly Calcite or Aragonite)
fossil
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Chert (within Limestone)
Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3) matrix
sedimentary
Chert (Cherty Limestone / Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Jasper
Jasper (Cryptocrystalline Quartz; SiO2)
sedimentary
Fossil Coral
Hexagonaria or Rugose coral fossil (replaced by silica/chalcedony)
fossil
Fossilized mammoth molar fragment
Proboscidean molar enamel and dentine, commonly Mammuthus spp.
fossil
Fossil shark tooth
Likely fossilized shark tooth, possibly Otodus megalodon
fossil
Yellow Chert (Yellow Jasper)
Silicon dioxide (SiO2)
sedimentary
Tiger's Eye (Nodule/Tumbled)
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
metamorphic
Chalcopyrite
CuFeS2
mineral
Ammonite fossil
Fossilized ammonoid cephalopod; likely an indeterminate Jurassic–Cretaceous ammonite
fossil
Fossilized bivalve shell fragment
Pectinid or related scallop bivalve; shell originally composed mainly of calcite (CaCO₃)
fossil
Polished ammonite fossil
Ammonoidea (likely a Jurassic or Cretaceous ammonite), preserved in limestone/mudstone
fossil
Pyrite (likely massive pyrite specimen)
Iron disulfide, FeS₂; cubic/isometric sulfide mineral
mineral
Blue-green fluorite crystal
Fluorite (calcium fluoride, CaF₂)
mineral
Banded Jasper (Mookaite / Chert)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Tiffany Stone
Fluorite-bearing Opalized Breccia
Rock/Mineralized Nodule
Fossilized tooth fragment, likely mammalian
Mineralized dentine and enamel; exact taxon indeterminate from the photograph
fossil
Fossilized Shark Tooth
Chondrichthyes tooth
fossil
Fossilized Coral
Anthozoa (Fossilized)
Sedimentary / Fossil
Fossilized Bone
Vertebrate Fossil Fragment (Calcium Phosphate / Hydroxyapatite)
fossil
Chert Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized shell or coral fragment
Likely silicified or calcitic marine invertebrate fossil; exact taxon indeterminate from the image
fossil
Fossil Coral
Hexagonaria / Rugosa / Scleractinia
fossil
Dinosaur Fossil (Skull)
Dinosauria fossilis (Petrified Hydroxyapatite / Calcium Carbonate)
sedimentary
Coprolite
Coprolite (fossilized feces)
sedimentary