Fossil

Sandstone with Trace Fossils

Arenite / Quartzwacke with Ichnofossils

Fossiliferous Flint / Chert

Microcrystalline quartz (SiO2) with embedded invertebrate fossils

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Fossiliferous Limestone

CaCO3 (principally Calcite or Aragonite)

Likely petrified wood

Silicified wood, chiefly microcrystalline quartz (SiO₂)

Fossiliferous limestone with a shell fossil

Calcite-rich limestone (primarily CaCO₃), containing a likely fossil shell

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with marine fossils

Mixed collection of polished pebbles, including probable fossiliferous limestone

Unidentified sedimentary rocks; the gray pebble with circular fossils may be bioclastic limestone

Fossil-bearing limestone (possible shell fossil)

Fossiliferous limestone, composed mainly of calcite (CaCO₃)

Fossiliferous Limestone with Crinoid Stem

Bioclastic Limestone (CaCO3)

Fossiliferous Limestone

Biogenic Sedimentary Rock (CaCO3)

Fossiliferous Limestone

Limestone (Calcium Carbonate, CaCO3)

Fossiliferous limestone

Calcite-rich carbonate rock (CaCO₃), likely bioclastic limestone

Fossilized coral or stromatoporoid

Calcareous fossil, likely colonial coral (phylum Cnidaria) or stromatoporoid sponge; commonly calcite/aragonite replaced by calcite

Weathered fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃)

Brachiopod Fossil in Shale

Phylum Brachiopoda (often species of Order Spiriferida or Rhynchonellida)

Crinoidal Limestone

Fossiliferous Limestone containing Crinoid stem fragments (Echinodermata)

Likely weathered vesicular volcanic rock

Probable basaltic scoria or vesicular andesite; exact identification requires testing

Sandstone and Mixed Rock Assemblage

Clastic Sedimentary Rock / Quartz Arenite

Sandstone and Gravel Aggregate

Clastic Sedimentary Rock / Quartzose Sandstone

Fossiliferous limestone

Bioclastic carbonate rock, chiefly calcite (CaCO₃)

Chert Nodule in Limestone

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3)

Petrified Wood

Siliconized Wood (SiO2)

Weathered limestone (probable)

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

Weathered limestone fragment

Limestone, composed primarily of calcite (CaCO₃)

Weathered limestone fragment

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

Weathered limestone

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

Fossiliferous limestone

Bioclastic carbonate rock, chiefly calcite (CaCO₃)

Fossil bivalve shell, likely oyster or related mollusk

Fossilized oyster-like bivalve; exact genus and age cannot be determined from the photograph

Weathered fossil-bearing limestone

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

Fossiliferous limestone

Bioclastic calcarenite, predominantly calcite (CaCO₃)

Orbicular jasper (orbicular chert)

Silica-rich microcrystalline quartz, SiO₂; orbicular jasper/chert with concentric silica bands

Rounded limestone pebble

Limestone; predominantly calcite (CaCO₃), possibly micritic or fossiliferous

Rounded fossiliferous limestone or weathered limestone nodule

Likely bioclastic limestone, composed mainly of calcite (CaCO₃); exact identification is limited by the blurry image

Vesicular basalt (likely weathered scoria)

Basaltic volcanic rock; chiefly plagioclase, clinopyroxene, and olivine with vesicles

Orbicular granite (likely rapakivi-type granite)

Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Weathered chert or silicified limestone nodule

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

Sandstone (Quartzose)

Arenite (SiO2 based)

Sandstone

Arenite (primarily SiO2)

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with fossil inclusions

Fossil bivalve shell

Fossilized mollusk (Bivalvia), likely oyster or related species; exact genus requires locality and preparation

Weathered sandstone fragment

Clastic sandstone, composed mainly of quartz and feldspar grains cemented by silica, calcite, or iron oxides