Fossil bivalve shell
Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features
fossil
Category
Sedimentary (Fossilized)
Browse sedimentary (fossilized) specimens identified by the Rock Identifier community.
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Fossilized Oyster Shell
Ostrea / Exogyra (Phylum Mollusca)
fossil
Petoskey Stone
Hexagonaria percarinata
fossil
Coral Fossil (Petrified Coral)
Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)
sedimentary
Fossiliferous Chert (Gryphaea Fossil)
Silicon Dioxide (SiO2) with Calcitic Mollusk Remnants
sedimentary
Fossilized Wood (Petrified Wood)
Silicified Wood (primarily quartz/chalcedony replacing organic matter)
Sedimentary (with some aspects of mineral replacement)
Fossilized Coral (Petoskey Stone type)
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Banded Agate
Cryptocrystalline variety of Quartz (SiO2)
mineral
Dendritic Agate
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
mineral
Amygdaloidal Basalt with Quartz/Zeolite Infill
Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)
igneous
Orthoceras Fossil in Limestone
Orthoceras (extinct genus of cephalopods), mineralized as Calcite (CaCO3) in Fossiliferous Limestone
sedimentary
Polished amber
Amber (fossilized plant resin; chiefly polymerized diterpenoid resin)
gemstone
Petoskey Stone
Hexagonaria percarinata
fossil
Baltic Amber (Raw)
Succinite
fossil
Ammolite
Biogenic gemstone (Aragonite, CaCO3)
mineral
Mammoth Tooth
Mammuthus tooth fossil
fossil
Amber with dark mineral/organic inclusions
Fossilized plant resin (amber; chiefly polymerized diterpenoid resin)
gemstone
Fulgarite
Fulgurite (Lechatelierite / Vitrified Sand)
igneous
Fossil Coral
Hexagonaria or Rugose coral fossil in limestone/silica matrix
fossil
Crinoid Stem Fossil
Crinoid Columnal (Phylum Echinodermata)
fossil
Tree Agate
Silicon Dioxide (SiO2) with Dendritic Inclusions
Mineral
Amber
Succinicum (Organic compound, primarily C10H16O)
Organic Gemstone (Mineraloid)
Shark Tooth Fossil
Lamniformes (Shark tooth fossil composed of Fluorapatite)
fossil
Fossil Shark Tooth
Carcharhinidae or Lamniformes sp. (possibly Carcharodon or Otodus genus)
fossil
Amber
Organic gemstone (Succinite)
mineral
Fossil shell fragment
Likely a fossilized brachiopod or bivalve; exact taxon cannot be determined from the image
fossil
Fossilized Shark Tooth
Elasmobranchii (fossilized matrix/root section)
fossil
Fossiliferous Limestone with Brachiopods
Calcium Carbonate (CaCO3) with fossilized Brachiopoda sp. (likely Order Spiriferida or Rhynchonellida)
sedimentary
Petoskey Stone / Fossilized Coral
Hexagonaria percarinata
fossil
Sandstone with trace fossil
Sandstone, possibly with Skolithos or similar trace fossil
sedimentary
Fulgurite
Fulgurite (Lechatelierite / Vitreous Silica)
mineral
Tree Agate
Silicon Dioxide (SiO2) with Dendritic Inclusions
gemstone
Lepidodendron Fossil (Scale Tree)
Lepidodendron sp.
fossil
Dendritic Quartz
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
mineral
Amber
Succinite (fossilized tree resin), C10H16O
Organic Gemstone
Fossil Coral (Favosites Honeycomb)
Favosites (Genus), Phylum Cnidaria, Class Anthozoa
sedimentary
Fossilized Coral (Petoskey Stone precursor)
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Amber
Succinite (a Fossilized Tree Resin); Chemical formula is approximately C10H16O
Organic mineraloid
Tumbled amber-like chalcedony or resinous fossil material
Likely chalcedony (microcrystalline SiO₂), though the appearance could also indicate copal/amber
gemstone
Petoskey Stone
Hexagonaria percarinata
fossil
Amber
Succinite (formula varies, primarily C10H16O)
Mineraloid (Organic)
Amber
Succinicum (Organic Gemstone - Resinite)
mineraloid