Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Category
Mineraloid (Human Made Geological Specimen)
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Basalt with Peridotite (Olivine) Xenolith
Olivine-rich Peridotite (Dunite) xenolith in Vesicular Basalt; chemical formula (Mg,Fe)2SiO4
igneous
Porphyritic Basalt (with Augite Crystals)
Porphyritic Mafic Volcanic Rock (Fe-Mg Silicates)
igneous
Conglomerate
Conglomerate (a clastic sedimentary rock)
Sedimentary
Banded Iron Formation (Jasper-Hematite)
Banded Iron Formation (BIF); composition primarily Hematite (Fe2O3) and Chalcedony/Quartz (SiO2)
sedimentary
Vesicular Basalt (Scoria)
Vesicular Basalt
igneous
Amphibolite with Hornblende
Amphibole-rich Metamorphic Rock (Ca2(Mg,Fe)5Si8O22(OH)2)
metamorphic
Granite
Granite (Felsic Plutonic Rock)
igneous
Biotite Mica
K(Mg,Fe)3AlSi3O10(OH)2
Mineral in a matrix (likely quartz or feldspar)
Sandstone
Clastic sedimentary rock (primarily SiO2)
sedimentary
Garnet Schist
Almandine Garnet-Mica Schist (X₃Y₂(SiO₄)₃)
metamorphic
Pumice
Pumice (a volcanic glass, primarily SiO2 with Al2O3)
igneous
Calcite
Calcite (CaCO3)
Mineral
Crushed Granite Gravel
Granite (Mainly Quartz, Feldspar, and Mica)
igneous
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
igneous
Unakite
Unakite (Altered Granite consisting of Orthoclase KAlSi3O8, Epidote Ca2(Al,Fe)3(SiO4)3(OH), and Quartz SiO2)
metamorphic
Sandstone (Cross-bedded Drill Core)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Pumice (Volcanic Rock)
Vesicular volcanic rock (composed largely of amorphous volcanic glass)
igneous
Basalt (Greenstone)
Amygdaloidal Basalt / Chloritized Basalt
Igneous
Coquina
Biogenic Limestone
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Moqui Marble (Shaman Stone)
Iron Oxide Concretion (composed primarily of Quartz sand with Hematite/Goethite shell)
sedimentary
Rhodonite beads (possibly dyed or treated, or lower quality Rhodonite)
Manganese inosilicate, (Mn,Fe,Mg,Ca)SiO3
Mineral
Granite with Mafic Inclusions
Granite (Phaneritic igneous rock composed of Quartz, Feldspar, and Mica)
igneous
Ironstone Concretion (Moqui Marble Type)
Goethite/Hematite-cemented Sandstone Concretion
sedimentary
Banded Iron Formation (BIF) / Tiger Iron variety
Banded Iron Formation (predominantly Hematite, Magnetite, and Chert/Quartz - SiO2 + Fe2O3)
sedimentary
Amygdaloidal Basalt with Quartz/Zeolite Infill
Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)
igneous
Citrine
Quartz (SiO₂)
mineral
River Pebble (Likely Chert or Fine-Grained Sandstone/Quartzite)
Siliciclastic clast (likely Chert or Quartzarenite/Quartzite pebble)
Sedimentary
Sandstone (Red)
Arenite (primarily SiO2 with Iron Oxide staining)
sedimentary
Almandine Garnet in Schist
Almandine Garnet (Fe3Al2(SiO4)3) in Mica Schist
metamorphic
Sandstone Concretion
Moqui Marble / Ironstone Concretion (Iron oxide-cemented sandstone)
sedimentary
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Coquina
Biogenic Limestone (Calcite, CaCO3)
sedimentary
Quartz (Smoky/Milky variety with inclusion)
Silicon Dioxide (SiO2)
mineral
Obsidian
Volcanic Glass (SiO2, usually 70% or more)
igneous
Pyrite
Iron Sulfide (FeS2)
mineral
Sand Dollar Fossil
Echinoidea (Clypeasteroida)
sedimentary
Milky Quartz Pebbles
Silicon Dioxide (SiO2)
mineral
Beach Pebble (likely Quartz or Chalcedony)
Silicon Dioxide (SiO2)
Mineral