Vesicular Basalt with Epidote
Vesicular Basalt (Mg, Fe)2SiO4 with Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))
igneous
Category
Rock
Browse rock specimens identified by the Rock Identifier community.
River Rocks (Black)
Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts
Sedimentary
Scoria
Scoria
Igneous
Druzy Quartz on Chert/Siltstone
Silicon Dioxide (SiO2) on Microcrystalline Silica/Siltstone matrix
sedimentary
Granite Pebble
Granite
igneous
Shale
Argillaceous Rock
sedimentary
Likely weathered granite or granitic gneiss
Granite: quartz + feldspar + mica; possibly gneiss if the faint texture reflects foliation
igneous
Granite with a polished dark-red granite cobble
Granite; predominantly quartz, feldspar, and mica
igneous
Weathered garnet-bearing gneiss
Quartz–feldspar–mica gneiss with almandine garnet, chiefly Fe₃Al₂(SiO₄)₃
metamorphic
Rounded gray river pebble, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene, possibly olivine)
igneous
Quartzite River Stone
Quartzite (SiO2)
metamorphic
Geode
Quartz / Chalcedony nodule
sedimentary
Mudstone
Argillite
sedimentary
Ferrous Slag (Iron Smelting By-product)
Fused Siliceous Slag
Anthropogenic Material (Man-made Rock)
Sandstone (Painted)
Arenite (primarily SiO2)
sedimentary
Quartzite Pebble
Metamorphic Quartzite (SiO2)
metamorphic
Gneiss (Pebble)
Gneiss
metamorphic
Brecciated Jasper
Silicon Dioxide (SiO2) with Hematite impurities
sedimentary
Chert (Yellow/Tan Variety)
Chert (SiO2)
sedimentary
Serpentine (Serpentinite)
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Vesicular Basalt
Extrusive mafic igneous rock
igneous
Grey Limestone Pebble
Limestone (Calcium Carbonate - CaCO3)
sedimentary
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Slate with Quartz Vein
Foliated Metamorphic Rock (Mainly Quartz, Muscovite, Chlorite)
metamorphic
Druzy Quartz on Matrix (likely Limestone or Sandstone)
Silicon Dioxide (SiO2) with various trace impurities
Mineral on Sedimentary Rock
Vesicular Basalt (Scoria)
Aphanitic Mafic Igneous Rock (Vesicular Basalt)
igneous
Quartz Druzy (on Matrix)
Silicon Dioxide (SiO2)
mineral
Sandstone or Mudstone
Sedimentary Rock
sedimentary
Conglomerate
Conglomerate Rock
sedimentary
Conglomerate
Conglomerate Rock
sedimentary
Porphyry
Porphyritic Rock
igneous
Conglomerate
Conglomerate rock
sedimentary
Quartz Vein in Host Rock
Hydrothermal Quartz (SiO2) in Slates/Schists
metamorphic
Quartz vein in weathered host rock
Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix
mineral
Brecciated quartz vein rock
Quartz (SiO₂), with iron-oxide staining and likely feldspar/carbonate gangue
mineral
Sandstone Concretion
Moqui Marble / Ironstone Concretion (Iron oxide-cemented sandstone)
sedimentary
Conglomerate (Quartz Pebble Conglomerate)
Quartz Pebble Conglomerate
sedimentary
Tumbled amber-colored agate or chalcedony
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/agate
mineral
Rounded quartz-rich river pebble
Lithic clast, likely quartzite or fine-grained sandstone
sedimentary
Rounded quartz-rich pebble
Chert or quartzite pebble (tentative; mostly microcrystalline quartz, SiO₂)
sedimentary
Quartz Crystal Cluster on Matrix
Silicon Dioxide (SiO2)
mineral
Agate
Silicon Dioxide (SiO2) - variety Chalcedony
mineral