Rock (Likely Sedimentary)

Shale and Pebble Fragment

Sedimentary Rock (Mudstone/Shale with Silica Pebble)

Mudstone

Argillite / Siliciclastic sedimentary rock

Unakite (likely epidote–feldspar rock)

Epidote–K-feldspar–quartz aggregate; commonly approximated as pink orthoclase/microcline + green epidote + quartz

Epidote (or Epidote-rich rock)

Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Vesicular volcanic rock, likely pumice or scoriaceous rhyolite

Vesicular rhyolite/dacite; predominantly silica-rich volcanic glass with feldspar and quartz

Quartz Pebble (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Angelite

Anhydrite (Calcium Sulfate, CaSO4)

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety, likely a orthogneiss or paragneiss depending on parent rock)

River Stone (likely Basalt or Gabro)

Mafic Igneous Rock

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible feldspar, mica, and iron-oxide staining

Agate (Carnelian-like)

Chalcedony (Silicon Dioxide, SiO2)

Fine-grained mafic rock, likely basalt or altered basalt

Basalt; chiefly plagioclase feldspar and pyroxene, with possible chlorite/serpentine alteration

Weathered quartz-rich rock, likely granite or granitic gneiss

Granite (quartz–feldspar–mica aggregate), possibly weathered granitic gneiss

Geode

Quartz nodule / Chalcedony-lined cavity

Quartz pebble

Quartz (Silicon Dioxide, SiO2)

Limestone with Lichen/Algae

Sedimentary Calcium Carbonate (CaCO3)

Shale

Laminated Fissile Pelite

Quartz geode

Microcrystalline quartz and drusy quartz (SiO₂), commonly lining a chalcedony-rich cavity

Milky quartz with iron-oxide staining and matrix

Quartz, silicon dioxide (SiO₂), likely massive quartz

Yellow Quartzite (River Pebble)

Quartzite (primarily SiO2 with iron oxide inclusions)

Granite

Granite (Phaneritic intrusive igneous rock)

Iron-rich quartzite or ironstone

Ferruginous quartzite; predominantly quartz (SiO₂) with hematite/goethite (Fe₂O₃/FeO(OH))

Dyed Pink Agate

Silicon Dioxide (SiO2) with artificial dye

Red Granite

Phaneritic Felsic Igneous Rock

Granite Fragment

Felsic Plutonic Rock (Granite)

Basalt with Fusion Crust (Meteorite-like appearance)

Vesicular Basalt

Weathered metallic sulfide-bearing rock, possibly chalcopyrite ore

Likely chalcopyrite (CuFeS₂) in a weathered host rock; identification is uncertain from the photograph

River Stone (Basalt Porphyry)

Porphyritic Basalt

Diorite or Granodiorite Pebble

Intermediate Phaneritic Igneous Rock

Fossiliferous Limestone Pebble

Calcium Carbonate (CaCO3) with Biogenic Inclusions

Porphyritic Basalt (with Olivine or Quartz phenocryst)

Porphyritic Basalt (Mafic Extrusive)

Weathered quartz-rich cobble, possibly milky quartz with iron staining

Quartz (SiO₂), likely with iron-oxide/hydroxide coatings and minor host-rock inclusions

Quartz

Quartz (SiO₂ - Silicon Dioxide)

Granite Cobble

Phaneritic Felsic Igneous Rock

Granite

Granite (Felsic Plutonic Rock)

Quartz (likely milky/rose quartz variety)

Quartz (SiO2 - Silicon Dioxide)

Rounded gray pebble, likely basalt or andesite

Fine-grained volcanic rock, probably basaltic-andesite; exact identification requires testing

Weathered Basalt

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Basalt River Stone

Basalt (Mafic volcanic rock)

Granodiorite Pebble

Granodiorite