Rock (Likely Sedimentary)

River Rock (likely Basalt or Greywacke)

Basalt or Lithic Sandstone

Fossilized Bone Chunk

Permineralized Vertebrate Bone (indeterminant)

Fossil trilobite

Trilobita (likely a spiny or enrolled trilobite; exact genus unclear)

Weathered sandstone or iron-rich sedimentary rock

Clastic sandstone, likely ferruginous sandstone; primarily quartz (SiO₂) with iron-oxide cement

Weathered iron-rich rock, likely laterite or ironstone

Goethite–hematite-bearing ferruginous laterite/ironstone; exact identification requires testing

Pyrite in Matrix (Quartz/Schist)

Iron Sulfide (FeS2)

Banded gneissic rock

Gneiss, likely quartz–feldspar–biotite gneiss

Banded metamorphic rock, likely mica schist

Mica schist, probably muscovite–biotite schist with quartz and feldspar

Decorative polished pebbles

Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt

Concrete or asphalt-like aggregate surface with a dark fragment

Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock

Weathered sandstone (likely arkosic sandstone)

Clastic sandstone, chiefly quartz and feldspar (SiO₂-rich framework)

Weathered iron-stained rock, likely sandstone

Iron-oxide-stained quartz-rich sandstone (tentative identification)

Chert (Jasper-bearing)

Chert (Silicon Dioxide, SiO2)

Weathered volcanic rock, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; primarily plagioclase feldspar, pyroxene, and possibly olivine or iron oxides

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Garnet-bearing gneiss

Biotite–garnet gneiss, typically quartz + feldspar + biotite + almandine garnet

Likely weathered chert or siliceous shale

Cryptocrystalline quartz (SiO₂), possibly with clay minerals

Tan quartz-rich rock, likely sandstone or weathered quartzite

Quartz sandstone; primarily SiO₂ with possible feldspar and iron-oxide cement

Weathered foliated metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and mineral tests

Weathered brown quartz-rich rock, likely sandstone

Quartz-rich sandstone (indeterminate lithology)

Rounded granite or granitic gneiss cobble

Granite–gneiss, chiefly quartz, feldspar, and mica

Sandstone (Flagstone)

Arenite (composed primarily of SiO2)

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly quartz-bearing

Rounded brown pebble, likely sandstone or weathered iron-rich rock

Indeterminate; possibly ferruginous sandstone (quartz-rich sedimentary rock)

Banded gneiss pebble

Gneiss, likely quartz–feldspar–mica gneiss

Sandstone (likely Arkosic or Lithic Sandstone)

Clastic Sedimentary Rock (SiO2 with assorted minerals)

Fossiliferous limestone pebble

Bioclastic limestone, commonly calcitic (CaCO₃)

Fossil fish impression or partial fish fossil

Indeterminate fossilized fish; likely compressed vertebrate remains in sedimentary rock

Iron-stained breccia or weathered conglomerate pebble

Clastic sedimentary rock; likely quartz-rich sandstone/breccia with dark mafic or iron-manganese fragments

Likely weathered sandstone or iron-stained limestone fragment

Indeterminate clastic carbonate/siliciclastic rock; likely quartz-rich sandstone or porous limestone with iron-oxide staining

White pebbles (rock material not identifiable from the image)

Undetermined; the smooth, pale pieces could be quartz, quartzite, or another light-colored rock

Fossiliferous Limestone with Crinoid Stem fragment

Calcite (CaCO3) containing Crinoidea fossils

Rounded gray river pebble

Indeterminate; likely weathered basalt, andesite, or fine-grained graywacke

Sandstone or Quartzite with algae

Unknown specific, largely SiO2 with biological growth

Weathered sedimentary cobble, likely limestone or calcareous sandstone

Indeterminate carbonate-rich clastic rock; possibly micritic limestone or calcarenite

Smooth gray pebbles

Unidentified rounded rock fragments; composition cannot be determined from the image

Limestone with Chert or Siltstone bands

Sedimentary carbonate rock (CaCO3) often with siliceous impurities

Chert (Pebble)

Microcrystalline silica (SiO2)

Quartz Geodes and Crystal Clusters

Silicon Dioxide (SiO2)

Banded gneiss (probable)

Quartz–feldspar–mica gneiss; composition commonly dominated by quartz, feldspar, and biotite/hornblende

Weathered iron-rich sandstone or ferruginous quartzite

Ferruginous sandstone; possibly hematite/goethite-cemented quartzite

Limestone (probable fossiliferous limestone)

Calcite-rich carbonate rock; predominantly CaCO₃ (calcite)