Sedimentary (Fossiliferous)

Fossiliferous Limestone (containing Brachiopods)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Fossiliferous Limestone with Brachiopod shell

Calcium carbonate (CaCO3)

Weathered flint or chert nodule

Microcrystalline quartz (SiO₂), commonly flint/chert

Limestone

Micritic limestone, chiefly calcite (CaCO₃)

Weathered sandstone

Quartz-rich sandstone, chiefly SiO₂ with feldspar and lithic grains

Calcite-rich limestone

Limestone, predominantly calcite (CaCO₃), possibly recrystallized

Chalky limestone

Micritic limestone, predominantly calcite (CaCO₃)

Weathered limestone

Calcite-rich limestone (predominantly CaCO₃)

Sandstone

Arenite (SiO2 primarily)

Weathered limestone or calcareous concretion

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃), commonly calcite

Sandstone

Arenite (Sedimentary rock composed of sand-sized grains)

Porous limestone (likely fossiliferous limestone)

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃)

Limestone

Calcitic limestone (predominantly calcium carbonate, CaCO₃)

Chalky limestone

Micritic limestone, chiefly calcite (CaCO₃)

Weathered limestone with possible fossil or calcite coating

Limestone; primarily calcium carbonate (CaCO₃), chiefly calcite

Weathered, porous limestone (probable fossiliferous limestone)

Calcite-rich limestone; predominantly CaCO₃

Limestone (with potential fossil inclusions)

Calcium Carbonate (CaCO3)

Layered shale or mudstone fragment

Fissile claystone/mudstone, commonly clay minerals with quartz and minor iron oxides

Fossiliferous Limestone with Quartz Veining

Limestone (Calcium Carbonate, CaCO3)

Mixed beach pebbles and shell fragments

Mostly carbonate rocks, likely limestone/calcarenite, with mollusk-shell bioclasts; exact species cannot be determined visually

Petrified Wood

Fossilized Wood (SiO2 replacing organic matter)

Fossil brachiopod or bivalve shell

Likely a fossilized brachiopod; precise genus cannot be determined from the photograph

Chert or silicified sedimentary fragment (tentative)

Microcrystalline quartz (SiO₂), possibly silicified limestone or fossil-bearing chert

Weathered chert or silicified limestone nodule

Microcrystalline quartz (SiO₂), possibly replacing limestone; exact identification requires testing

Weathered fossiliferous limestone or fossil fragment

Indeterminate bioclastic carbonate rock; likely calcite (CaCO₃) with fossil shell material

Chert (and Limestone)

Silicon Dioxide (SiO2)

Weathered limestone

Calcite-rich limestone (CaCO₃), possibly fossiliferous or micritic

Chalky limestone fragment

Micritic limestone, chiefly calcite (CaCO₃)

Tumbled yellow chalcedony (likely silicified material)

Microcrystalline quartz, SiO₂; possibly iron-stained chalcedony or fossilized/silicified limestone

Fossiliferous limestone with silicified fossil material

Bioclastic limestone; likely marine mollusk/coral fragments, locally replaced by chalcedony or calcite

Fossiliferous limestone with brachiopod or bryozoan fossils

Calcite (CaCO₃) limestone containing marine invertebrate fossils, possibly brachiopoda or bryozoa

Weathered limestone (likely fossiliferous limestone)

Calcite-rich carbonate rock, predominantly CaCO₃

White limestone, possibly chalky limestone

Calcite-rich carbonate rock; predominantly calcium carbonate (CaCO₃)

Weathered porous limestone (probable fossil-rich carbonate fragment)

Calcite-dominated carbonate rock; CaCO₃

Porous limestone (likely fossiliferous limestone)

Calcite-rich limestone; predominantly calcium carbonate (CaCO₃), possibly bioclastic or reef limestone

Likely limestone or calcareous shale

Calcite-rich carbonate rock; predominantly calcium carbonate (CaCO₃), possibly micritic limestone

Fossiliferous limestone, likely coral or shell-rich limestone

Biogenic calcite (CaCO₃), commonly limestone containing fossil coral or mollusks

Fossiliferous limestone with a fossil sea urchin

Bioclastic limestone containing an echinoid fossil (class Echinoidea)

Likely fossiliferous limestone or dolostone

Micritic limestone, chiefly calcite (CaCO₃), possibly dolomitized; apparent fossil or stylolitic markings

Polished fossiliferous limestone (probable crinoidal limestone)

Calcite-rich limestone; chiefly CaCO₃, with possible crinoid fossil fragments

Fossiliferous iron-rich breccia/conglomerate

Clastic sedimentary rock containing lithic fragments and possible fossil or concretionary structures; iron oxides/hydroxides (hematite–goethite)

Fossiliferous limestone (coral or shell-fragment limestone)

Bioclastic limestone, predominantly calcite (CaCO₃)