Sedimentary (Fossiliferous)

Orange sandstone

Quartz-rich sandstone, commonly ferruginous sandstone

Weathered sandstone fragment

Quartz-rich sandstone, likely ferruginous sandstone

Likely limestone fragment

Limestone, predominantly calcite (CaCO₃)

Tumbled limestone or dolostone pebble

Calcite-rich limestone (CaCO₃), possibly dolostone (CaMg(CO₃)₂)

Likely sandstone

Quartz-rich sandstone (indeterminate variety)

Weathered sandstone or iron-rich quartzite fragment

Quartz-dominated siliciclastic rock; likely ferruginous sandstone (SiO₂-rich)

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, predominantly CaCO₃; possibly fossiliferous limestone

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, chiefly calcium carbonate (CaCO₃), possibly with quartz grains

Porous limestone or calcareous sandstone

Calcite-rich carbonate rock; chiefly CaCO₃, possibly with quartz and clay

Rounded limestone pebble

Limestone, predominantly calcite (CaCO₃)

Unidentified weathered rock fragment

Likely limestone or sandstone; exact identification is not possible from the photograph

Tumbled pale limestone or calcite-rich stone

Limestone, chiefly calcite (CaCO₃); exact identification is uncertain from the photograph

Weathered sandstone fragment

Quartz-rich sandstone, likely arkosic or lithic sandstone

Likely limestone or marble fragment

Calcite-rich carbonate rock; CaCO₃

Tan chert or fine-grained sandstone fragment

Microcrystalline quartz (SiO₂), possibly chalcedony-rich chert

Banded chert or flint

Microcrystalline quartz (SiO₂), likely with iron-oxide and dark organic/mineral impurities

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, likely limestone (CaCO₃), possibly sandy or dolomitic

Likely limestone or chalk fragment

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

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Likely fossiliferous limestone fragment

Calcitic limestone, chiefly calcium carbonate (CaCO₃; mineral calcite)

Weathered limestone fragment

Limestone, chiefly calcite (CaCO₃), possibly fossiliferous or dolomitic

Weathered fossil-bearing limestone

Bioclastic limestone, chiefly calcite (CaCO₃), possibly containing a brachiopod or coral fossil

Fossiliferous shale or slate with plant impressions

Carbonaceous mudstone/shale; possible fossil plant material (often fern-like impressions)

Rounded gray pebble, likely limestone or weathered sandstone

Probably micritic limestone (calcite, CaCO₃) or quartz-rich sandstone; exact identification requires testing

Fossiliferous limestone / shell hash rock

Bioclastic limestone (calcarenite or coquina), dominantly CaCO₃

Polished fossiliferous limestone (likely crinoidal or coral limestone)

Bioclastic carbonate rock, chiefly calcite (CaCO₃)

Fossiliferous limestone (coral-rich limestone)

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

Rounded fossiliferous limestone pebble

Micritic limestone, chiefly calcite (CaCO₃), with possible fossil or solution cavities

Chert (Fossiliferous Chert/Flint)

Silicon Dioxide (SiO2)

Weathered fossiliferous limestone pebble

Calcitic limestone, predominantly CaCO₃ (likely containing fossil or bioclast fragments)

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Fossil shell impression or shell-bearing limestone

Indeterminate bioclastic carbonate; likely mollusk fragment preserved in limestone or mudstone

Limestone

Calcium Carbonate (CaCO3)

Likely calcite-rich limestone or marble fragment

Calcite (CaCO₃), probably micritic limestone; exact identification requires testing

Sandstone

Arenite

Small rounded limestone pebble

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

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃), possibly fossiliferous or dolomitic

Weathered limestone cobble

Limestone, predominantly calcite (CaCO₃), possibly fossiliferous micrite

Weathered limestone or calcareous rock

Calcite-rich limestone (predominantly CaCO₃), possibly fossiliferous

Weathered limestone or calcitic fossil/reef fragment

Calcite-rich limestone (CaCO₃), possibly fossiliferous limestone

Weathered limestone or calcareous sandstone

Calcite-dominated carbonate rock (CaCO₃), possibly fossiliferous limestone