Coal (most likely Bituminous or Anthracite)
Coal (organic sedimentary rock)
Category
Browse synthetic polymer (synthetic material) specimens identified by the Rock Identifier community.
Coal (most likely Bituminous or Anthracite)
Coal (organic sedimentary rock)
Coal (most likely Bituminous or Anthracite)
Bituminous Coal (Grade of Coal), Anthracite (Grade of Coal)
Chert / Flint
Chert (varieties include Flint)
Iron Meteorite
Iron-Nickel Meteorite (primarily composed of kamacite and taenite alloys)
Citrine
Quartz (SiO2) - variety Citrine
Jasper
Silicon Dioxide (SiO2) - a variety of Chalcedony (Cryptocrystalline Quartz)
Seraphinite
Clinochlore (Mg,Fe)5Al(AlSi3O10)(OH)8 - specific variety for Seraphinite due to its fibrous inclusions and chatoyancy.
Travertine (used in construction, not a 'specimen' in situ)
Travertine
Magnetite
Magnetite (Fe3O4)
Granite (likely a river or beach pebble)
Granite (a felsic intrusive igneous rock primarily composed of quartz, feldspar, and mica)
Rose Quartz
Quartz (SiO₂), specifically a variety of Quartz
Basalt
Basalt
Pyrite
Pyrite (Iron Disulfide), FeS2
Granite
Granite (a felsic intrusive igneous rock)
Pebble
Clast (specifically a granule or small pebble)
Chert or Flint (polished/water-worn)
Chert (a microcrystalline or cryptocrystalline variety of quartz, SiO2). Flint is a specific variety of chert.
Mookaite Jasper
Siliceous sedimentary rock (variety of Jasper/Chert)
Petrified Wood
Silicified wood, primarily composed of Quartz (SiO2)
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Coquina
Coquina (a type of limestone)
Granite
Granite (Felsic intrusive igneous rock)
Peridot (likely, given the color and bead form)
Olivine, variety Peridot (Mg,Fe)2SiO4
Clear Quartz (Rock Crystal)
Quartz (SiO₂)
Granite
Granite (Felsic intrusive igneous rock)
Chalcedony or Chert/Jasper with secondary mineral staining
SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.
Agate
Agate (Cryptocrystalline Variety of Quartz, SiO2)
Ferruginous Sandstone
Sandstone, Iron-rich
Banded Chert
Chert (a microcrystalline variety of quartz, SiO2 with minor impurities)
Chert (varieties include Flint or Jasper)
Chert (cryptocrystalline quartz; SiO₂)
Chert
Siliceous sedimentary rock (predominantly microcrystalline quartz, SiO2)
Conglomerate (Puddingstone)
Conglomerate (specifically, clastic sedimentary rock)
Shale
Shale (fine-grained clastic sedimentary rock)
Agate
Agate (a variety of Chalcedony, SiO2)
Quartzite
Quartzite (primarily SiO2)
Quartz (Float/Abraded)
Quartz (SiO₂)
Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)
Quartz (SiO₂)
Peridot
Olivine (specific variety: gem-quality forsterite), (Mg,Fe)2SiO4
Biotite Mica
K(Mg,Fe2+)3(Al,Fe3+)Si3O10(OH,F)2
Bauxite Ore
Hydrated aluminum oxides (e.g., Gibbsite Al(OH)3, Boehmite ̲̲̲̲AlOOH, Diaspore ̲̲̲̲AlOOH)
Banded Calcite or Travertine
Calcium Carbonate (CaCO3)
Chert
Chert (microcrystalline quartz)
Ocean Jasper
Orbicular Jasper (variety of Chalcedony - SiO2)