Fossiliferous Limestone
Limestone (Calcium Carbonate, CaCO3)
Category
Browse mineral (biogenic) specimens identified by the Rock Identifier community.
Fossiliferous Limestone
Limestone (Calcium Carbonate, CaCO3)
Bay Scallop Shell
Argopecten irradians (Biogenic Calcium Carbonate / CaCO3)
Fossil oyster shell
Fossilized bivalve, likely Ostrea or Crassostrea; calcite (CaCO₃) shell
Pearl necklace with small blue-green gemstone accents
Pearls: nacre, chiefly aragonite (CaCO₃) and conchiolin; accents appear to be turquoise or similar opaque blue-green stone
Tahitian Black Pearl
Biogenic Calcium Carbonate (Aragonite/Conchiolin Mixture), CaCO3
Banded chert or flint
Microcrystalline quartz (SiO₂), likely with iron-oxide and dark organic/mineral impurities
Likely fossilized shell or carbonate concretion
Indeterminate biogenic calcium carbonate, commonly calcite (CaCO₃)
Spondylus Oyster Calcification / Fossilized Oyster
Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
Red coral beads
Precious coral, commonly Corallium rubrum (calcium-carbonate skeleton)
Pearl stud earrings
Pearl, primarily aragonite (CaCO₃) and conchiolin
Chalky limestone
Micritic limestone, predominantly calcite (CaCO₃)
Chert (likely chalcedony-rich flint)
Microcrystalline quartz, SiO₂ (quartz/chalcedony)
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
Fossilized Shell in Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
Coquina
Biogenic Limestone (Calcium Carbonate - CaCO3)
Wampum / Quahog Shell Fossil Fragment
Mercenaria mercenaria (Calcium carbonate, CaCO3)
Chert (or Petrifed Wood / Banded Flint)
Silicon Dioxide (SiO2)
Chert (Flint)
Chert (SiO2)
Flint or chert fragment
Microcrystalline quartz (SiO₂), commonly chalcedony with possible iron-oxide impurities
Green Chert (Jasper / Flint)
Silicon Dioxide (SiO2)
Coal (Bituminous or Anthracite)
Organogenic Sedimentary Rock (Carbon)
Fossiliferous Limestone
Carbonate sedimentary rock with trace fossils (CaCO3)
Fossiliferous Limestone
Fossiliferous Limestone (CaCO3)
Fossiliferous Limestone
Bioclastic Limestone (CaCO3)
Fossil Shell in Sedimentary Matrix
Bivalvia (fossil) in Calcium Carbonate Matrix
Chert
Cryptocrystalline Quartz (SiO2)
Seashell (Cockle Shell)
Cardiidae (Bivalvia), primary composition: Calcium Carbonate (CaCO3) in the form of aragonite or calcite
Vesicular Limestone with Borings
Fossiliferous Calcarenite (Calcium Carbonate, CaCO3)
Limestone with Fossil Impression
Calcium Carbonate (CaCO3)
Coquina / Fossiliferous Limestone
Fossiliferous Calcarenite (Calcium carbonate, CaCO3)
Limestone with Fossil inclusions
Fossiliferous Limestone (CaCO3)
Oyster Shell (Biogenic Calcium Carbonate)
Crassostrea virginica (or related species) - Calcium Carbonate (CaCO3)
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with Biogenic Fossils
Worn quartz-rich pebble
Likely microcrystalline quartz (SiO₂), possibly a weathered chert or milky quartz fragment
Likely weathered chert or siliceous shale
Cryptocrystalline quartz (SiO₂), possibly with clay minerals
Pearl
Biogenic calcium carbonate; mainly aragonite (CaCO₃), sometimes calcite, in nacre
Sea Shell Fragment (Calcium Carbonate)
Aragonite / Calcite (CaCO3)
Fossiliferous limestone, likely coralline or stromatolitic
Biogenic limestone; predominantly calcite (CaCO₃)
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
Fossiliferous Chert
Cryptocrystalline quartz (SiO2) with biogenic inclusions
Fossiliferous Limestone
Calcite (CaCO3) matrix with biogenic fragments