Organic (Biological Specimen)

Fossilized bivalve shell

Recrystallized calcium-carbonate shell, commonly fossil oyster or clam (Bivalvia)

Fossil-bearing limestone, possibly a crinoid or shell fragment

Calcite (CaCO₃) limestone containing an indeterminate marine fossil

Amber

Succinite (C10H16O)

Polished fossil shell fragment

Fossilized bivalve or gastropod shell, likely calcitic/aragonitic carbonate

Botryoidal calcite (likely calcite concretion)

Calcite, calcium carbonate (CaCO₃)

Amber

Succinite (specifically for Baltic amber; general formula C10H16O)

Pyrite

Iron Disulfide (FeS2)

Marine gastropod shell

Calcareous mollusk shell, primarily aragonite (CaCO₃), likely a whelk or conch

Polished fossiliferous limestone, likely fossil shell fragment

Calcite-rich limestone (CaCO₃), possibly bioclastic/coquina limestone

Fossilized shell or coral fragment

Indeterminate calcareous fossil; likely aragonite/calcite (CaCO₃)

Green Calcite

Calcite (CaCO3)

Fossilized shell fragment, likely bivalve

Bivalvia indet.; commonly preserved as calcite (CaCO₃) shell material

Fossil-bearing limestone slab

Bioclastic limestone, likely containing brachiopod or bivalve impressions

Fossilized shell or coral fragment

Likely silicified or calcitic marine invertebrate fossil; exact taxon indeterminate from the image

Small weathered fossil or mineral fragment

Indeterminate; possibly fossilized shell, bone, or a pale carbonate mineral

Fossilized shell fragment

Indeterminate fossil mollusk; likely a silicified or mineral-replaced bivalve/gastropod fragment

Likely vertebra fossil or bone fragment

Indeterminate fossilized vertebra; mineralized hydroxyapatite, commonly Ca₅(PO₄)₃(OH)

Fossilized coral (likely tabulate or colonial coral)

Fossil coral; possibly Hexagonaria or related Paleozoic colonial coral

Pyrite

Iron Sulfide (FeS2)

Chert / Jasper

Microcrystalline Quartz (SiO2)

Fossil shark tooth

Likely fossilized shark tooth, possibly Carcharhinus or Otodus species

Fossilized coral or bryozoan fragment

Indeterminate colonial coral/bryozoan fossil; likely calcitic calcium carbonate (CaCO₃)

Fossiliferous Shale

Carbonaceous Shale (with potential plant/aquatic fossils)

Fossil coral, likely solitary rugose coral

Rugosa (possibly colonial tabulate coral); calcite/aragonite replaced by calcite

Porous limestone (likely coral limestone)

Calcite-rich carbonate rock; primarily calcium carbonate, CaCO₃

Tooth fossil, likely mammalian or reptilian fragment

Indeterminate fossilized tooth; enamel and dentine, taxon unresolved

Weathered chert or flint

Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from photo

Fossiliferous Sandstone (with Brachiopod or Bivalve mold)

Clastic Sedimentary Rock with Macrofossil Mold

Fossilized oyster or other bivalve shell

Calcitic bioclast, commonly Ostrea spp. or Exogyra spp.

Selenite desert rose

Gypsum (CaSO₄·2H₂O), rosette habit

Chert (Green Fossilized Algae or Jasper)

Silicon Dioxide (SiO2)

Fossilized Shark Tooth

Carcharocles sp. or similar (Fossilized Fluorapatite)

Kidney Stone

Calcium Oxalate (CaC2O4·nH2O)

Ambergris

Ambrein (C30H52O)

Massive calcite (likely limestone-derived calcite)

Calcite, calcium carbonate (CaCO₃); possibly a chalky limestone fragment

Pyrite

Iron Sulfide (FeS2)

Fossilized ammonite

Ammonoidea (likely a small, chambered ammonite fossil)

Carved limestone architectural fragment

Limestone, predominantly calcite (CaCO₃), possibly weathered fossiliferous or oolitic limestone

Polished fossiliferous agate

Chalcedony (microcrystalline SiO₂), likely containing fossil coral or stromatoporoid structures

Sandstone (Weathered Cobble)

Clastic sedimentary rock (primarily SiO2)

Fossil shark tooth, likely sand tiger shark

Fossilized selachian tooth; possibly *Carcharias* or *Striatolamia*

Likely weathered limestone or calcitic marble

Calcite (CaCO₃), probably micritic limestone; marble is a possible metamorphic alternative