Chert or flint (weathered brown variety)
Microcrystalline quartz, SiO₂ (chalcedonic quartz)
sedimentary
Category
Sedimentary (Biogenic)
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Tumbled dark flint/chert
Microcrystalline quartz (SiO₂), commonly with chalcedony and iron-oxide impurities
sedimentary
Chert (Flint / Chalcedony pebble)
Silicon Dioxide (SiO2)
sedimentary
Chert or flint with chalcedony/quartz veins
Microcrystalline silica: primarily quartz (SiO₂), including chalcedony; possible fossiliferous limestone or silicified material
sedimentary
Pearl
Biogenic CaCO3 (Aragonite)
mineral
Chert (Flint / Jasper / Hornstone)
Microcrystalline Quartz (SiO2)
sedimentary
Green Chert (Jasper / Flint)
Silicon Dioxide (SiO2)
sedimentary
Fossiliferous Limestone
Biogenic Sedimentary Rock (primarily CaCO3 with fossil fragments)
sedimentary
Hag Stone
Perforated Sedimentary Rock (typically Limestone or Sandstone)
sedimentary
Devil's Toenail
Gryphaea (extinct genus of foam oysters, typically composed of Calcite CaCO3)
sedimentary
Chert (Agate / Jasper pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Banded chert or siliceous mudstone
Microcrystalline quartz (chalcedony), SiO₂; possibly ferruginous shale
sedimentary
Fossilized Tooth
Vertebrate Fossilized Tooth (Mineralized Biogenic Material)
fossil
Scallop Shell Fossil
Pecten sp.
fossil
Flint or chert fragment
Microcrystalline quartz (SiO₂), likely flint/chert
sedimentary
Calcite-rich limestone (possibly fossiliferous limestone)
Calcite, CaCO₃, in a limestone matrix
sedimentary
Chert (Flint)
Microcrystalline or cryptocrystalline quartz (SiO2)
sedimentary
Chert (and Flint variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint) / Silicified Limestone
Microcrystalline Quartz (SiO2)
sedimentary
Calcite in Matrix
Calcium Carbonate (CaCO3)
mineral
Fossiliferous Limestone
Calcium Carbonate (CaCO3) matrix with biogenic fragments
fossil
Fossiliferous Limestone
Fossiliferous Limestone (CaCO3)
sedimentary
Fossiliferous Limestone (Coquina / Shell Limestone Egg)
Biogenic Limestone (composed primarily of Calcite, CaCO3)
sedimentary
Beach Pebbles and Quartz Aggregates
Quartz pebbles and biogenic fragments (SiO2, CaCO3)
sedimentary
Bay Scallop Shell
Argopecten irradians (Biogenic Calcium Carbonate / CaCO3)
sedimentary
Coquina
Biogenic Limestone (mostly Calcium Carbonate, CaCO3)
sedimentary
Chert (likely chalcedony-rich flint)
Microcrystalline quartz, SiO₂ (quartz/chalcedony)
sedimentary
Iron-stained chert or siliceous mudstone
Microcrystalline quartz (SiO₂), likely chert with hematite/goethite staining
sedimentary
Weathered chert or silicified limestone nodule
Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃)
sedimentary
Spondylus Oyster Calcification / Fossilized Oyster
Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)
sedimentary
Fossilized tooth or jaw fragment (likely fish or reptile)
Indeterminate vertebrate bone/tooth; mineralized hydroxyapatite, commonly Ca₅(PO₄)₃(OH)
fossil
Pearl (Biogenic)
Nacre / Calcium Carbonate (CaCO3)
mineral
Mookaite Jasper
Silicified Radiolarite (SiO2)
sedimentary
Banded Chert / Agate
Silicon Dioxide (SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Limestone with Calcite Veining
Calcium Carbonate (CaCO3) - Biogenic/Chemical Sedimentary Rock
sedimentary
Flint or chert fragment
Microcrystalline quartz (SiO₂), likely flint/chert
sedimentary
Chert (likely brown flint)
Microcrystalline quartz, SiO₂ (chalcedonic quartz aggregate)
sedimentary
Oyster Shell (Biogenic Calcium Carbonate)
Crassostrea virginica (or related species) - Calcium Carbonate (CaCO3)
sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
sedimentary
Fossiliferous Limestone
Biogenic Limestone containing marine invertebrate fossils
sedimentary
Fossil oyster shell
Ostrea or Exogyra sp. (identification uncertain)
fossil