Limestone

Lapis Lazuli

Complex rock composed mainly of lazurite, calcite, and pyrite

Flint

SiO2 (Microcrystalline Quartz)

Flint

SiO2 (Cryptocrystalline Quartz)

Lapis Lazuli

Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

Polished fossiliferous limestone

Fossiliferous micrite/bioclastic limestone, likely crinoidal or shell-rich limestone

Fossilized Brachiopod Shell Fragment

Brachiopoda (Class: Rhynchonellata or Strophomenata)

Cockle Shell Fossil

Cardiidae family (Bivalvia)

Chert (Nodule / Geode fragment)

Microcrystalline Quartz (SiO2)

Weathered blue-gray calcite/aragonite fragment

Calcium carbonate (CaCO₃), probably calcite; possibly shell-derived aragonite

Fossiliferous Limestone

Calcareous Sedimentary Rock (CaCO3)

Weathered limestone

Limestone, predominantly calcite (CaCO₃), possibly fossiliferous

Chert Nodule in Limestone

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3)

Fossiliferous Limestone (Coquina / Shell Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Fossiliferous Limestone (Coquina / Shell Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Fossiliferous Limestone (Coquina / Shell Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Rounded limestone pebble

Micritic limestone, composed mainly of calcite (CaCO₃)

Weathered limestone

Micritic limestone, primarily calcite (CaCO₃)

Land Snail Shell

Gastropoda (Calcium Carbonate, CaCO3)

Fossiliferous limestone (probable crinoidal limestone)

Calcite-rich carbonate rock; chiefly CaCO₃, with fossil crinoid fragments

Fossiliferous limestone, possibly coral limestone

Calcite-rich carbonate rock; chiefly calcium carbonate (CaCO₃), with probable fossil coral or shell structures

Fossiliferous limestone (coral-rich limestone)

Bioclastic carbonate rock, composed mainly of calcite (CaCO₃), with fossilized colonial coral or bryozoan material

Fossiliferous limestone, likely coral limestone

Bioclastic calcite (CaCO₃), commonly derived from fossil coral or shell material

Limestone (River Pebble / Fossiliferous Limestone)

Calcium Carbonate (CaCO3)

Limestone (specifically Bituminous or Carbonaceous Limestone)

Calcium Carbonate (CaCO3) with Organic Impurities

Limestone (specifically Dolomitic/Crystalline Limestone)

Sedimentary Carbonate Rock (CaCO3 / CaMg(CO3)2)

Fossiliferous limestone

Bioclastic calcitic limestone (predominantly CaCO₃)

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

Porous limestone

Calcareous limestone, primarily calcite (CaCO₃)

Fossiliferous Limestone

Fossiliferous Limestone (CaCO3 with organic inclusions)

Fossiliferous Limestone

Bioclastic Limestone (Calcium Carbonate, CaCO3)

Chalky limestone

Micritic limestone, predominantly calcite (CaCO₃)

Chalky limestone

Micritic calcite limestone; predominantly CaCO₃

Fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃)

Fossiliferous Limestone

Bioclastic Limestone (Calcium Carbonate, CaCO3)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)