Rock (Likely Sedimentary)

Red Sandstone

Arenite (SiO2 with Fe2O3)

Small weathered rock fragment, likely iron-stained sandstone

Probable quartz-rich sandstone (dominant mineral: SiO₂); exact identification is uncertain from the image

Sandstone (likely Greywacke or Siltstone variety)

Arenite / Siltstone (primarily SiO2)

Rounded gray pebble

Unidentified lithic pebble; likely quartz-rich sandstone, quartzite, or fine-grained igneous rock

Weathered sedimentary rock, possibly sandstone

Indeterminate clastic sediment; probable quartz-rich sandstone

Gray Limestone Fragment

Limestone (CaCO3)

Chert (likely chalcedony-rich flint)

Microcrystalline quartz, SiO₂ (quartz/chalcedony)

Mixed sedimentary rock and mineral specimens

Predominantly limestone, chert, sandstone, and iron-oxide-bearing clasts; exact identification requires testing

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with marine fossils

Rounded brown-gray stone, possibly weathered conglomerate or sandstone

Indeterminate clastic sedimentary rock; likely poorly cemented sandstone/conglomerate

Banded Sedimentary Rock (Siltstone/Mudstone with concretion)

Siltstone with Ferruginous Banding

Rounded river pebble, likely sandstone or weathered quartz-rich sedimentary rock

Indeterminate siliciclastic pebble; likely quartz–feldspar sandstone, with possible iron-oxide staining

Polished granitic pebble

Granite, composed chiefly of quartz, feldspar, and mica/amphibole

Quartz Sand/Gravel

Silicon Dioxide (SiO2)

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

Weathered granitic rock

Granite, chiefly quartz + feldspar + mica; possibly a pale granodiorite

River Rock (Mossy)

Stream-rounded Clast (likely Siltstone or Sandstone with bryophytes)

Sandstone (Quartz-rich)

Arenite (composed primarily of SiO2)

Likely weathered limestone

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

Sandstone (likely Quartzose)

Arenite (primarily SiO2)

Sandstone (Ferruginous)

Arenite with iron oxide cement (Fe2O3)

Quartz (Sunstone-like Chalcedony)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Painted River Pebble (likely Basalt or Greywacke)

Aphanitic Lithic Clast with Anthropogenic Pigment coating

Rounded quartz-rich pebbles, likely jasper/chert with one iron-stained specimen

Microcrystalline quartz (SiO₂), possibly jasper or chert; exact identification is uncertain from the image

Weathered granite pebble

Granite, mainly quartz, feldspar, and mica; approximate composition SiO₂-rich continental crust

Iron-rich brown stone, possibly weathered chert or ironstone

Undetermined; likely iron-oxide-bearing silica-rich rock (chert/ironstone)

Fossiliferous Shale

Laminated Mudrock with plant fossils

Polished jasper or chert

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (primarily SiO2)

Chert (River Cobble)

Chert (Cryptocrystalline Quartz, SiO2)

Rounded sandstone pebble

Quartz-rich sandstone; commonly arkose or lithic sandstone

Small weathered rock fragment

Indeterminate; possibly carbonate-rich sandstone or limestone

Rounded dark river pebble

Likely fine-grained basalt or andesite; exact identification requires a fresh surface or tests

Sandstone (likely Fossiliferous)

Arenite / Fossiliferous Sandstone (SiO2 composition)

River Stone (composed of Siltstone/Basalt mixture)

Siltstone or microcrystalline Basalt pebble

Weathered sandstone or iron-stained limestone fragment

Likely quartz-rich sandstone (SiO₂) or calcitic limestone (CaCO₃); exact identification requires testing

Weathered granitic or feldspathic pebble

Likely granite/granodiorite; quartz–feldspar–mica aggregate

Sandstone (likely Arkosic or Lithic)

Clastic Sedimentary Rock (composed predominantly of sand-sized grains, 0.0625 to 2 mm)

Chert (Gray Chalcedony)

Microcrystalline Quartz (SiO2)

Fossil-bearing sedimentary rock, possibly fossil wood or bone

Indeterminate silicified/carbonate fossil in sandstone or mudstone

Sandstone (likely Siltstone or Mudstone)

Clastic sedimentary rock (primarily SiO2 with various oxides)