Sedimentary (Fossiliferous)

Tumbled limestone pebble

Limestone, primarily calcite (CaCO₃)

Hag Stone (Holey Rock / Fossiliferous Limestone)

Limestone (CaCO3) with natural erosion / fossil cavities

Fossiliferous Limestone

Calcium carbonate (CaCO3) matrix with fossil inclusions

Fossiliferous limestone

Bioclastic limestone, likely containing fossil gastropods or other marine invertebrates; mainly calcite (CaCO₃)

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Weathered iron-rich limestone or calcareous sandstone

Calcite-rich carbonate rock, possibly ferruginous limestone (CaCO₃ with iron oxides)

Weathered limestone or calcareous concretion

Calcite-rich carbonate rock; primarily CaCO₃

Red sandstone fragment

Quartz-rich sandstone, likely ferruginous arkose or subarkose

Likely weathered limestone

Calcite-rich limestone (mostly CaCO₃), possibly dolomitic limestone

Weathered sandstone or iron-rich sedimentary rock

Sandstone, likely quartz-rich with iron-oxide staining

Red sandstone

Quartz-rich sandstone, commonly arkose or ferruginous sandstone

Weathered limestone

Limestone, predominantly calcite (CaCO₃)

Tumbled brown chert or weathered sandstone pebbles

Microcrystalline quartz (chert), possibly iron-stained sandstone; SiO₂ dominant

Red sandstone fragment

Ferruginous sandstone, composed mainly of quartz (SiO₂) with iron-oxide cement

Weathered limestone or dolostone

Micritic limestone, primarily calcite (CaCO₃), possibly dolomite (CaMg(CO₃)₂)

Weathered gray stone, likely limestone

Calcite-rich limestone (CaCO₃), possibly dolomitic limestone

Weathered sandstone or siltstone pebble

Clastic sedimentary rock, likely quartz-rich sandstone (dominantly SiO₂)

Weathered shale or mudstone outcrop

Fine-grained siliciclastic sedimentary rock, chiefly clay minerals, quartz, and feldspar

Weathered light-colored stone, likely limestone

Calcitic limestone; predominantly calcium carbonate (CaCO₃), possibly chalky or dolomitic

Weathered sandstone fragment

Quartz-rich sandstone, likely feldspathic or lithic sandstone

Weathered limestone slab

Micritic limestone, primarily calcite (CaCO₃)

Iron-stained sandstone or weathered ironstone concretion

Quartz-rich sandstone, locally cemented by iron oxides (hematite/goethite); exact identification requires testing

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Dark shale or slate fragment

Carbonaceous shale, possibly low-grade slate; composition mainly clay minerals, quartz, and organic carbon

Fossil-bearing Sedimentary Rock

Sedimentum cum fossili

Fossil-bearing limestone

Bioclastic limestone, chiefly calcite (CaCO₃), with embedded fossil fragments

Weathered sandstone or iron-stained sedimentary rock

Likely quartz-rich sandstone; exact identification is uncertain from the photograph

Chert Nodule (Fossiliferous Chert)

Microcrystalline Quartz (SiO2)

Flint or chert flake

Microcrystalline quartz (SiO₂), likely fossiliferous or cortex-bearing chert

Weathered limestone or calcareous fossil fragment

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

Fossiliferous limestone with a bivalve fossil

Calcareous sedimentary rock; likely molluscan shell fossil, composed chiefly of calcite (CaCO₃)

Fossiliferous Limestone (Pink/Red)

Calcium Carbonate (CaCO3) with Bioclasts

Fossiliferous Chert (with Fossil Shells)

Silicon Dioxide (SiO2) with biogenic inclusions

Fossiliferous Limestone (Crinoid stem)

CaCO3 (Calcium Carbonate) with Fossil Inclusions

Likely limestone or pale sandstone fragment

Calcite-rich carbonate rock (limestone) or quartz-rich sandstone; image is insufficient for confident species identification

Weathered sandstone or limestone fragment

Likely quartz-rich sandstone; possibly calcarenite or weathered limestone

Crushed Limestone

Calcium Carbonate (CaCO3)

Light-colored limestone (likely chalky or calcitic limestone)

Calcite-rich limestone; primarily calcium carbonate, CaCO₃

Light-colored limestone or marble fragment

Calcite-rich carbonate rock; likely limestone (CaCO₃), possibly recrystallized marble

Weathered sandstone

Quartz-rich clastic sedimentary rock, commonly arkose or lithic sandstone