Unknown Rock Specimen
igneous
Category
Rock
Browse rock specimens identified by the Rock Identifier community.
Sandstone
Arenite
sedimentary
Eroded Brick or Pumice-like Scoria
Vesicular Basalt / Scoria (Anthropogenic variant: Eroded Firebrick)
igneous
Greenstone (likely chlorite- or epidote-rich metamorphic rock)
Greenstone; commonly metamorphosed basalt or dolerite, with chlorite, epidote, and actinolite
metamorphic
Fossilized gastropod shell
Gastropoda indet.; shell originally composed mainly of aragonite (CaCO₃)
fossil
Small rounded pebble, likely basalt
Fine-grained mafic volcanic rock (likely basalt); image alone cannot confirm composition
igneous
Granite
Granite
igneous
Andesite Porphyry
Andesite Porphyry
Igneous
Painted River Rock
Artificially Coated Sedimentary Rock
sedimentary
Green serpentine (likely serpentine-rich stone)
Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; composition approximately Mg₃Si₂O₅(OH)₄
metamorphic
Banded gneiss pebble
Gneiss, commonly quartz–feldspar–mica gneiss
metamorphic
Granite
Phaneritic Igneous Rock (Granite)
igneous
Sandstone (Micaceous)
Clastic Sedimentary Rock (primarily SiO2 with Mica)
sedimentary
Basalt with Quartz/Calcite Veins
Basalt with hydrothermal vein infill
igneous
Druzy Quartz on Sandstone
Silicon Dioxide (SiO2) with Quartz Crystals on Clastic Sedimentary Rock
sedimentary
Quartz Vein Rock
Quartz (Silicon Dioxide, SiO2)
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Rounded quartz-rich pebble
Lithic pebble; likely quartz/quartzite with iron-oxide staining
sedimentary
River Stone (Sedimentary Sandstone/Quartzite)
Arenite/Quartzite transition specimen
sedimentary
Banded Sandstone Peabble
Arenite with iron oxide banding
sedimentary
Rounded quartz-rich pebble
Likely granitoid-derived quartz–feldspar rock; exact identification uncertain from image
igneous
Quartz Druzy (Geode Fragment)
Silicon Dioxide (SiO2)
mineral
Sandstone with Quarzite clasts
Arenite (SiO2 based)
sedimentary
Chert (Agatized/Chalcedony variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Bone in Matrix
Vertebrata fossil
fossil
White Agate
SiO2 (Microcrystalline Quartz)
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Likely mica-rich schist
Mica schist, probably muscovite- or biotite-bearing; exact minerals cannot be confirmed from the photo
metamorphic
Biotite-bearing granite or granitic gneiss
Quartz–feldspar–biotite granite; possibly weakly foliated granitic gneiss
igneous
Micaceous schist (likely biotite schist)
Biotite–quartz–feldspar schist; commonly containing muscovite and/or garnet
metamorphic
Fossil bivalve or brachiopod in sedimentary rock
Unidentified fossil shell impression; likely a ribbed bivalve or brachiopod preserved in shale/siltstone
fossil
Likely weathered basalt or andesite fragment
Fine-grained volcanic rock, likely basaltic-andesite; exact identification requires testing
igneous
Basalt
Extrusive Igneous Rock
igneous
Basalt Pebble
Extrusive Igneous Rock
igneous
Shale
Clastic Sedimentary Rock
sedimentary
Rounded gray stone, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; likely basalt (plagioclase ± pyroxene, possibly olivine)
igneous
Basalt
Basalt (Mafic volcanic rock)
igneous
Sandstone
Clastic sedimentary rock (primarily SiO2)
sedimentary
Basalt with Granite Inclusions (Xenoliths)
Mafic igneous rock (Basalt) with Sialic minerals
igneous
Quartz-veined Mudstone or Argillite
SiO2 (Quartz) in Siltstone/Mudstone matrix
sedimentary
River Pebble (Quartzite or Chert)
Silicon Dioxide (SiO2)
metamorphic or sedimentary