Limestone

White limestone, possibly chalky limestone

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

Porous limestone (likely coral limestone)

Calcite-rich carbonate rock; primarily calcium carbonate, CaCO₃

Small rounded pebble, likely limestone or quartz-rich sedimentary fragment

Indeterminate lithic clast; probable micritic limestone (CaCO₃) or weathered quartz-rich stone

Crinoid Stem Fossil

Class Crinoidea (Echinodermata)

Calcite-rich limestone

Limestone, predominantly calcium carbonate (CaCO₃), usually calcite

Chert or silicified limestone nodule

Microcrystalline quartz (SiO₂), possibly replacing carbonate rock

Marble

Metamorphosed Limestone (main mineral: Calcite, CaCO3)

Likely calcite-rich limestone or marble

Calcite (CaCO₃); possibly recrystallized limestone (marble)

Chert (Flint)

Microcrystalline or cryptocrystalline quartz (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Limestone Nodule)

Silicon Dioxide (SiO2)

Likely tumbled yellow calcite or limestone fragment

Calcite (CaCO₃), possibly micritic limestone

Fossil coral pebble

Fossilized colonial coral, commonly Favosites or Hexagonaria

Fossil Coral (Petoskey Stone / Rugose Coral)

Hexagonaria percarinata (or similar fossilized rugose/tabulate coral)

Chert Nodule

Microcrystalline Quartz (SiO2)

Iron-stained chert or chalcedony nodule

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

Chert (flint), likely with iron-stained weathering rind

Microcrystalline quartz/chalcedony (SiO₂)

Fossil Coral

Tabulate Coral (potentially Favosites or Calapoecia)

Quartz Geode

Silicon Dioxide (SiO2) in a concretion

Chert (with Limestone/Carbonate matrix)

Sedimentary cryptocrystalline silica (SiO2)

Flint

Silicon dioxide (SiO2) - cryptocrystalline quartz

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Chert (and Flint variant)

Silicon Dioxide (SiO2)

Porous limestone

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

Chalky limestone

Micritic limestone, chiefly calcite (CaCO₃)

Fossiliferous limestone

Bioclastic limestone, predominantly calcite (CaCO₃)

Fossil-bearing limestone

Calcite-rich limestone (mainly CaCO₃), with a possible shell fossil

Weathered limestone (probable)

Calcite-rich limestone, chiefly calcium carbonate (CaCO₃)

Concrete-like limestone or cemented carbonate rock

Likely limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image

Fossiliferous Limestone

Biogenic Sedimentary Rock (Calcium Carbonate, CaCO3)

Beige polished stone tile (likely limestone or marble)

Uncertain; probable calcite-rich limestone or marble (CaCO₃)

Porous limestone fragment

Calcite-rich limestone (CaCO₃), possibly bioclastic limestone

Weathered limestone fragment

Calcitic limestone (mostly CaCO₃; possibly micritic limestone)

Weathered limestone or calcitic fossil/reef fragment

Calcite-rich limestone (CaCO₃), possibly fossiliferous limestone

Fossil-bearing limestone, likely with a shell fossil

Bioclastic limestone, composed mainly of calcite (CaCO₃); fossil appears to be a shell or shell cross-section

Crystalline limestone (marble-like calcite rock)

Calcite, CaCO₃; likely recrystallized limestone (marble)

Wollastonite

Calcium Inosilicate Mineral, CaSiO3

Weathered sandstone or limestone pebble

Likely quartz-rich sandstone (clastic sedimentary rock) or porous limestone; exact identification requires testing

Limestone (River Pebble)

Calcium Carbonate (CaCO3)

Limestone Pebble

Calcium Carbonate (CaCO3)

Limestone or Chalk

Calcium Carbonate (CaCO3)

Limestone (specifically fossiliferous/skeletal limestone)

Calcium Carbonate (CaCO3)