Sedimentary Rock (Possibly A Conglomerate Or Coarse Grained Sandstone)

Rounded brown cobble, likely weathered sandstone or iron-rich sedimentary rock

Indeterminate; possibly ferruginous sandstone or ironstone

Jasper Conglomerate (specifically Puddingstone)

Jasper Conglomerate (Siliceous sedimentary rock)

Concrete with Aggregate

Artificial Conglomerate (Cement and Aggregate)

Rounded river cobble, likely quartz-rich sandstone or quartzite

Indeterminate quartz-rich clastic rock; probable sandstone (SiO₂-rich)

Coarse Sandstone Pebble

Clastic Sedimentary Rock (Sandstone)

Graywacke

Lithic Sandstone (Graywacke)

Weathered quartz-rich granitoid (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz (SiO₂), feldspar, and minor mica/amphibole

Sedimentary Pebble

Sedimentary Rock Fragment

Conglomerate

Conglomerate

Gneiss

Gneiss (Metamorphic Rock)

Greywhacke (River Pebble)

Graywacke (immature sandstone)

Quartzite

Metamorphic Rock (Mainly SiO2)

Weathered quartz-rich rock, likely sandstone or quartzite

Quartz (SiO₂)-rich sandstone; possibly partially metamorphosed quartzite

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline quartz (SiO₂), possibly with mica and feldspar

Breccia

Breccia (Clastic sedimentary rock)

Metaconglomerate

Metaconglomerate (Quartzite conglomerate)

Light-colored weathered stone, possibly limestone or quartz-rich rock

Indeterminate; likely calcitic limestone (mostly CaCO₃) or quartz sandstone (SiO₂)

Quartz-rich sandstone or quartzite cobble

Quartz arenite; possibly weakly metamorphosed quartzite (SiO₂-dominant)

Puddingstone

Conglomerate

Siltstone/Sandstone (possibly Wonderstone or Picture Sandstone)

Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide inclusions)

Sandstone

Sandstone (composed primarily of sand-sized minerals or rock grains)

Rounded gray-brown river cobble

Indeterminate lithology; possibly weathered quartzite, chert, or fine-grained sandstone

Granite Gneiss

Gneiss (derived from granitic protolith)

Puddingstone (Jasper Conglomerate)

Conglomerate (specific type: Jasper Conglomerate or Hertfordshire Puddingstone)

Puddingstone

Conglomerate

Tumbled quartz-rich rock, likely granite or granitic gneiss

Granite/granitic gneiss; chiefly quartz (SiO₂), feldspars, and minor mica/amphibole

Granite / Arkosic Sandstone (Coarse Igneous or Sedimentary Aggregate)

Granite / Quartz-Feldspar Aggregate

Gneiss

Gneiss (High-grade metamorphic rock)

Conglomeratic volcanic breccia

Lithic volcanic breccia, likely andesitic or basaltic

Granite (possibly granitic gneiss)

Felsic plutonic rock dominated by quartz, K-feldspar, plagioclase, biotite and/or hornblende

Quartz on Sandstone

Silicon Dioxide (SiO2) in Lithic Sandstone

Fossiliferous Sandstone / Fossil Fragment

Fossiliferous Sedimentary Matrix with Indeterminate Fossil Material

Quartz (with inclusions / Sandstone fragment)

Silicon Dioxide (SiO2)

Conglomerate

Conglomerate

Rounded dark pebble, possibly weathered basalt

Fine-grained mafic volcanic rock; likely basalt, but identification is uncertain from the photograph

Iron-rich sandstone or ferruginous quartzite

Hematite/goethite-bearing quartz sandstone; possibly weakly metamorphosed to quartzite

Weathered quartz-rich sandstone or quartzite

Quartzite (predominantly SiO₂), possibly strongly cemented sandstone

Weathered rock fragment (likely granite or quartz-rich sandstone)

Uncertain; possible granitic fragment containing quartz and feldspar

Weathered quartz-rich rock, possibly sandstone or quartzite

Likely quartzite (mostly SiO₂), though a granular sandstone is also possible

Sandstone

Arenite

Likely weathered river pebble

Indeterminate lithology; possibly fine-grained sandstone, siltstone, or chert

Gneiss (or Granite Gneiss)

Metamorphic rock rich in quartz, feldspar, and biotite/amphibole