Basalt (River Stone)
Mafic volcanic rock
igneous
Category
Organic Structure (Not A Rock)
Browse organic structure (not a rock) specimens identified by the Rock Identifier community.
Hypersthene
Hypersthene ((Mg,Fe)SiO₃)
Mineral
Quartz (Rock Crystal) with minor impurities
Quartz (SiO2)
Mineral
Conglomerate (or Breccia)
Clastic Sedimentary Rock
sedimentary
Greenstone Porphyry
Porphyritic Metavolcanic Rock
igneous
Marble
Marble (primarily Calcite, CaCO3 or Dolomite, CaMg(CO3)2)
Metamorphic Rock
Gneiss (specifically Granitic Gneiss)
Gneissic Metamorphic Rock
metamorphic
Conglomerate
Conglomerate (Sedimentary rock)
sedimentary
Basalt
Mafic Igneous Rock
igneous
Banded Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Granite
Granite
igneous
Gneiss
Gneissic Metamorphic Rock
metamorphic
Petrified Wood
Silicified wood (Quartz/Chalcedony)
Sedimentary
River Rock (likely Siltstone or fine-grained Sandstone)
Clastic Sedimentary Rock
sedimentary
Vesicular Basalt
Mafic Igneous Rock
igneous
Quartz on Host Rock
Silicon Dioxide (SiO2)
Mineral Specimen
Gneiss
Gneiss (Metamorphic rock)
metamorphic
Shale
Lutaceous Sedimentary Rock
sedimentary
Conglomerate
Conglomerative Sedimentary Rock
sedimentary
Banded Gneiss
Gneiss (Metamorphic Rock)
metamorphic
River Cobble (likely Sandstone or Siltstone type)
Sandstone or Siltstone (common rock types that form river cobbles)
Sedimentary Rock (specifically a clastic sedimentary rock formed into a cobble)
Sandstone
Sandstone (clastic sedimentary rock, composed predominantly of sand-sized minerals or rock fragments)
Sedimentary Rock
Petrified Wood
Silicified wood, primarily composed of Quartz (SiO2)
Mineral, often found in sedimentary deposits
Gneiss (with Mica and Quartz)
Gneissic Metamorphic Rock
metamorphic
Boulder Opal
Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)
Mineral
Shatter Cone
Impactite (Shatter Cone texture)
metamorphic
Basalt with Quartz Veins
Amygdaloidal Basalt (matrix) with Crystalline SiO2 (veins)
igneous
Porphyritic Basalt (Chinese Writing Stone or Flower Stone)
Porphyritic Basalt / Porphyry
igneous
Yellow Jasper
Silicon Dioxide (SiO2) with hydrated iron oxide impurities (Goethite)
Mineral-based Sedimentary/Silica
Sandstone (Glacial Cobble)
Arenite / Sedimentary Rock (primarily SiO2)
sedimentary
Unakite (Epidote-Rich Granite)
Unakite (Granite consisting of Orthoclase, Quartz, and Epidote)
metamorphic
Lapis Lazuli
Lapis Lazuli (a rock, not a single mineral; primary mineral is Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2
Metamorphic rock
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Granite
Phaneritic Plutonic Felsic Rock (SiO2, KAlSi3O8, NaAlSi3O8, CaAl2Si2O8)
igneous
Opal
Hydrated Silica (SiO2·nH2O)
mineral
Undetermined Due to Blur (Possible Flesh-Tone Mineral)
Unknown (Insufficient Visual Clarity)
Mineral
Granite Pebble
Igneous Intrusive Rock (Quartz-Feldspar-Mica Phenocrysts)
igneous
Sandstone
Arenite (SiO2 predominantly)
sedimentary
Red Jasper (Amygdaloidal Basalt with Agate)
Silicon dioxide (SiO2) in Basalt host
igneous
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.
Igneous
Belemnoit (Fossil)
Belemnoidea (Order), Rostrum / Guard
sedimentary
Druzy Quartz
Silicon Dioxide (SiO2)
mineral