Sedimentary (Biogenic Sediment Or Biological Remain)

Tumbled dark stone, possibly chert or basalt

Indeterminate; likely fine-grained basalt (plagioclase–pyroxene) or microcrystalline chert (quartz, SiO₂)

Fossilized shell fragment, likely bivalve

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

Flint or chert fragment

Microcrystalline quartz (SiO₂), likely flint/chert

Banded chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chert/jasper with iron-oxide staining

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with Bioclasts

Fossiliferous Limestone

Biogenic Calcium Carbonate (CaCO3)

Carved limestone architectural fragment

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

Rounded brown pebble, likely chert or iron-stained quartzite

Chert (microcrystalline quartz, SiO₂) or quartzite (recrystallized quartz, SiO₂)

Devil's Toenail

Gryphaea (extinct genus of foam oysters, typically composed of Calcite CaCO3)

Yellow-brown chert or silicified rock

Microcrystalline quartz (SiO₂), possibly iron-stained chert

Fossil coral or shell fragment

Indeterminate calcareous fossil; likely aragonite or calcite (CaCO₃)

Fossiliferous limestone pebble

Calcite-rich limestone containing possible brachiopod or coral fossil impressions

Stromatolite

Biogenic sedimentary rock

Fossiliferous Limestone

Biogenic Sedimentary Rock

Dark flint or chert

Microcrystalline quartz (SiO₂), chiefly chalcedony with possible moganite

Flint (chert), likely brown flint

Microcrystalline quartz/chalcedony (SiO₂)

Fossiliferous Limestone

Biogenic Calcium Carbonate (CaCO3)

Likely fossilized shell or carbonate concretion

Indeterminate biogenic calcium carbonate, commonly calcite (CaCO₃)

Sandstone concretion

Arenite sedimentary rock (concretion/nodule)

Fossilized Shark Tooth (Partial) or Coprolite

Elasmobranchii (fossil) or Coprolite (trace fossil)

Polished brown flint/chert (likely)

Microcrystalline quartz, SiO₂ (chalcedonic flint/chert)

Banded Chert / Agate

Silicon Dioxide (SiO2)

Flint or chert fragment

Microcrystalline quartz (SiO₂), likely flint/chert

Chert (likely brown flint)

Microcrystalline quartz, SiO₂ (chalcedonic quartz aggregate)

Conglomerate

Conglomerate (clastic sedimentary rock)

Tahitian Pearl

Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3

Seashell fragment

Calcium carbonate (CaCO3)

Petrified Wood (Agatized/Silicified Wood)

Silicified Wood / Chalcedony (SiO2)

Seashell Fossil

Mollusca (Bivalvia)

Banded chert or siliceous sedimentary rock

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide staining and possible carbonate/clay layers

Fossiliferous Limestone

Limestone (CaCO3 - Calcium Carbonate)

Fossiliferous Limestone

Biogenic Limestone (CaCO3)

Tumbled chert or chalcedony pebble

Microcrystalline quartz (SiO₂), likely chert/chalcedony

Petrified Wood with Lichen

Silicified Wood (SiO2) colonized by crustose lichens

Chert or silicified rock fragment

Microcrystalline quartz (SiO₂), likely chert with iron-oxide staining

White coral limestone (probable fossiliferous limestone)

Calcite (CaCO₃), commonly derived from aragonitic coral skeletons recrystallized to calcite

Tumbled yellow-brown stone, likely chert or jasper

Microcrystalline quartz (SiO₂), possibly iron-stained chert/jasper

Polished septarian nodule

Calcite–aragonite–barite septarian concretion, commonly in a claystone or limestone matrix

Mosasaur Tooth Fossil

Mosasauridae (likely Prognathodon or Mosasaurus)

Possible fossilized bone or tooth fragment

Indeterminate fossilized vertebrate material; mineralized hydroxyapatite replaced or coated by silica/carbonate

Fossiliferous limestone pebble

Calcite-rich limestone, CaCO₃, with possible fossil or shell fragments

Weathered chert or flint

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