Olivine (Peridotite)
Magnesium iron silicate ((Mg, Fe)2SiO4)
igneous
Category
Not A Geological Specimen
Browse not a geological specimen specimens identified by the Rock Identifier community.
Learn about Not A Geological Specimen in the encyclopedia
View all →
Biotite Schist
Schist (Biotite-dominated)
metamorphic
Cannonball Concretion
Calcite-cemented sandstone concretion
sedimentary
Red Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Coral
Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)
sedimentary
Banded Gneiss Pebble
Banded Gneiss
metamorphic
Pegmatite (Quartz, Feldspar, and Tourmaline/Biotite)
Pegmatitic Igneous Rock
igneous
Petrified Wood / Red Jasper
Silicified wood (primarily Silicon Dioxide, SiO2)
sedimentary
Fossilized Gastropod in Limestone
Gastropoda (Class) in Fossiliferous Limestone
sedimentary
Limonite / Iron Oxide Concretion
Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O
mineral
Mica-rich metamorphic rock (likely schist)
Mica schist; commonly composed of muscovite and/or biotite, quartz, and feldspar
metamorphic
Weathered quartz-rich rock, possibly pegmatite
Likely quartz–feldspar pegmatite; exact identification is uncertain from the image
igneous
Ironstone Nodule
Ferruginous Concretion
sedimentary
Kambaba Jasper
Stromatolite (fossilized algae)
sedimentary
Sandstone with Quartz Crystal Infill
Quartz-cemented quartz arenite
sedimentary
Small flint/chert fragment (tentative)
Chert, microcrystalline quartz (SiO₂)
sedimentary
Graphic Granite
Graphic Granite (Granitic Pegmatite)
igneous
Peanut Wood
Silicified (Petrified) Wood - SiO2 (Silicon Dioxide)
sedimentary
Green Jasper / Metavesuvianite-bearing rock
Silica-rich microcrystalline quartz aggregate / Green Jasper
igneous
Conglomeratic gravel / pebble-rich concrete-like rock
Polymictic conglomerate (likely an unconsolidated gravel surface; exact identification uncertain from the image)
sedimentary
Breccia
Sedimentary Breccia
sedimentary
Dog (Sleeping)
Canis familiaris (or Canis lupus familiaris)
Organic/Biological
Smoky quartz and clear/white quartz bead necklace
Quartz, silicon dioxide (SiO₂); smoky variety colored by irradiation-related defects
gemstone
Quartzite (Lithic Artifact)
Quartzite (SiO2)
metamorphic
Chert (Arrowhead/Tool variety)
Microcrystalline Quartz (SiO2)
sedimentary
Likely serpentinite (rough green serpentinite rock)
Serpentinite, composed mainly of serpentine-group minerals (e.g., antigorite, lizardite, and chrysotile)
metamorphic
Amethyst
Quartz (Silicon Dioxide) SiO2 + Fe4
mineral
Fossilized Coral
Cnidaria (Anthozoa), often replaced by Calcium Carbonate (CaCO3) or Silica (SiO2)
sedimentary
Polished orbicular granite (likely orbicular diorite)
Orbicular granitoid; chiefly quartz, feldspar, and dark amphibole/biotite
igneous
Granite Pebble (River Rock)
Granite
igneous
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Likely anthracite coal
Anthracite, a high-rank coal composed chiefly of carbon
sedimentary
Graphic Granite
Graphic granite (alkali feldspar and quartz pegmatite)
igneous
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Porphyritic rhyolite (likely pink feldspar-rich volcanic rock)
Rhyolite, composed mainly of quartz and feldspar; exact identification needs closer examination
igneous
Desert Rose
Gypsum rosette (CaSO4·2H2O) or Barite rosette (BaSO4)
mineral
Fossil Coral (Petoskey Stone / Rugose Coral)
Hexagonaria percarinata (Order: Rugosa, Fossilized Calcium Carbonate CaCO3)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, SiO2)
mineral
Fossilized Burrow
Trace fossil (Ichnogenus)
fossil
Borehole Rock / Pierced Stone
Sedimentary rock with naturally eroded piddock clam boring (Hag Stone)
sedimentary
Septarian Nodule (Micro-fragment)
Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)
sedimentary