Not A Rock

Granite Pebble (Pegmatitic Quartz-Feldspar River Rock)

Granite / Quartz-Feldspar-Mica Aggregate

Sandstone with Desert Varnish

Arenite (SiO2 predominantly) with Ferromanganese coating

Iron-stained weathered rock

Unknown

Granite Pebble

Intrusive Igneous Rock

Weathered iron-rich rock, possibly limonite-bearing basalt or laterite

Indeterminate; likely Fe-oxide/hydroxide–altered mafic rock, dominated by limonite/goethite with silicate minerals

Limestone bedrock

Limestone, chiefly calcite (CaCO₃)

Pale greenish quartz-bearing rock, possibly serpentine or altered feldspar

Tentatively serpentinite-related rock (serpentine-group minerals) or altered granitic material; identification is uncertain from the photograph

Weathered geode or vug-bearing rock

Likely a quartz- or calcite-lined geode/vug in a host rock; exact minerals cannot be confirmed from the image

Red Sandstone

Arenite (primarily quartz with iron oxide cement)

Smooth gray pebbles

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

Granite

Granite

Rough garnet-bearing rock, likely almandine garnet in matrix

Almandine garnet, Fe₃Al₂(SiO₄)₃; exact host rock cannot be determined from the image

Copper Ore / Altered Granodiorite

Cupriferous rock with silicate gangue

Granite Pebble

Granite (Plutonic Igneous Rock)

Quartzite Pebble (Stream-rounded Quartz/Quartzite Gravel)

Quartzite / Silicon Dioxide (SiO2)

Granite

Granite; primarily quartz, feldspar, and mica

Weathered basalt or volcanic breccia

Fine-grained mafic volcanic rock, likely basalt (plagioclase–pyroxene ± olivine), possibly brecciated

Generic Pebble

Lithic Fragment

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4)

Granite

Granite

Shale

Fissile Mudstone (primarily composed of phyllosilicate minerals like kaolinite, montmorillonite, and illite)

Vesicular Basalt (or Scoria)

Mafic extrusive igneous rock with vesicles

Vesicular Basalt (Lava Rock)

Vesicular Basalt

Possibly garnet-bearing rock fragment

Unidentified reddish-brown mineral or rock; the image is insufficient for a reliable species identification.

Weathered gneissic or granitic rock

Quartz–feldspar–biotite gneiss (tentative; possibly weathered granite)

Quartz Vein in Amphibolite / Gneiss

Quartz (SiO2) in Mafic Metamorphic Host Rock

Rounded quartz-veined pebble

Likely quartz-veined metamorphic rock; exact host rock is indeterminate from the image

Unidentified dark pebble

Unknown

Lapis Lazuli

Lapis Lazuli (a rock, not a single mineral; primary mineral is Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

Serpentine

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

K-Feldspar Granite Fragment

Felsic Plutonic Rock (Granite)

Garnet Schist

Garnetiferous Micaceous Schist

Basalt

Extrusive mafic igneous rock

River Pebble (Granite/Gneiss)

Granitic Pebble / Quartz-Feldspar Aggregate

River Pebble (Siltstone / Fine-grained Sandstone)

Sedimentary Pebble (Siliclastic)

Quartzite Pebble (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Vesicular Basalt (or Scoraceous Basalt)

Basalt (Vesicular texture)

Unidentified rock fragments

Indeterminate; likely a weathered, iron-stained silicate rock

Smoky Quartz and Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Basalt with Xenolith

Extrusive Igneous Rock containing Mantle Xenolith

Chert (Jasper/Flint Pebble)

Microcrystalline quartz (SiO2)

Sandstone

Quartz Sandstone (predominantly)