Sedimentary Rock (Possibly A Conglomerate Or Coarse Grained Sandstone)

Sandstone

Sedimentary Rock (Quartz Sandstone)

Quartz-bearing conglomeratic rock with orange feldspar/calcite inclusion

Probably porphyritic granite or granitic pegmatite; exact identification requires a thin section or tests

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (primarily SiO2)

Quartz-rich rock, possibly quartzite

Quartzite (dominantly quartz, SiO₂); identification is provisional from the photo

Likely quartz-rich metamorphic rock (quartzite or milky quartz)

Quartzite; predominantly quartz (SiO₂), possibly with feldspar and iron-oxide staining

Rounded iron-rich pebble, possibly weathered laterite or ironstone

Ironstone/lateritic ferricrete; predominantly goethite–hematite with clay and quartz impurities

Pink granite

Granite, chiefly quartz, alkali feldspar and plagioclase with dark mica or amphibole

Tumbled quartz-rich pebble

Quartz (SiO₂), likely a rounded quartzite or quartz-rich sandstone pebble

Weathered brown sandstone or quartzite cobble

Indeterminate sandstone; possibly quartz-rich quartzite

Quartz Pebble (Water-worn Quartzite)

Silicon Dioxide (SiO2)

Breccia

Breccia

Aggregate Concrete

Anthropogenic Conglomerate (Technosol)

Weathered iron-rich sandstone or ironstone

Ferruginous sandstone, composed mainly of quartz (SiO₂) cemented by iron oxides such as hematite (Fe₂O₃) and goethite (FeO(OH))

Sandstone (with secondary weathering/concretion)

Arenite (composed primarily of Quartz, SiO2)

Likely quartz-rich stone (possibly quartzite)

Quartzite, composed predominantly of quartz (SiO₂)

Quartz-rich gneiss

Foliated quartz–feldspar–mica gneiss, possibly migmatitic

Siltstone River Rock

Siltstone (composed of silt-sized particles, silicate minerals)

Sandstone

Sandstone (clastic sedimentary rock composite)

Weathered quartz-rich rock, possibly quartzite or sandstone

Likely quartzite (mostly SiO₂), though heavily weathered sandstone is possible

Weathered sandstone

Quartz-rich clastic sandstone, likely iron-oxide stained

Quartz-rich polymict conglomerate (possibly hydrothermal breccia)

Clast-supported polymict conglomerate dominated by quartz; includes chalcedony/quartz and dark lithic clasts

Fragmented Sedimentary Pebble

Clastic Sedimentary Specimen

Tumbled gray quartz-rich stone, possibly quartzite or chert

Likely quartzite (microcrystalline SiO₂), though the photograph cannot distinguish it confidently from gray chert or silicified limestone

Sandstone

Arenite (Siliclastic sedimentary rock)

Conglomerate (pebble conglomerate)

Clastic sedimentary rock composed of rounded gravel-sized clasts in a finer matrix

Milky quartz-rich rock

Quartz (silicon dioxide, SiO₂), likely massive quartz with minor feldspar or host-rock material

Gneiss

Gneiss (Metamorphic Rock)

Fossiliferous Sandstone / Quartzite Pebble

Sedimentary rock with skeletal fragments (e.g., Paleozoic crinoid/brachiopod fossils)

Granite or granitic gneiss pebble

Quartz–feldspar–mica aggregate; likely weathered granite, possibly weakly gneissic

Weathered iron-stained quartzite or sandstone cobble

Quartzite (quartz, SiO₂), possibly ferruginous sandstone

Sandstone

Arenite

Granite or granitic gneiss boulders

Quartz–feldspar–mica granitoid; possibly banded gneiss

Sandstone

Arenite

Likely iron-rich sandstone or weathered hematite-bearing rock

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂ with iron oxides such as hematite/goethite)

Rounded sandstone pebble

Quartz-rich sandstone (primarily SiO₂), possibly arkosic sandstone

Uncertain gray-and-white rock fragment

Likely quartz-bearing granite or quartzite; exact identification requires testing

Weathered gray sandstone or fine-grained metamorphic rock

Likely quartz-rich sandstone (quartz arenite), possibly weakly metamorphosed metasandstone

Siltstone with Quartz Vein

Siltstone (primarily SiO2, Al2O3, Fe2O3)

Sandstone

Arenite (SiO2 composition primarily)

Sandstone (likely Siltstone or fine-grained Sandstone)

Sedimentary Rock (Clastic)

Banded gneiss (likely biotite-rich gneiss)

Gneiss; chiefly quartz, feldspar, biotite, and possibly hornblende

Iron-rich sandstone or weathered laterite fragment

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂ with iron oxides such as hematite/goethite)