Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Category
Browse organic mineraloid specimens identified by the Rock Identifier community.
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Jasper/Common Chert Pebble)
Microcrystalline Quartz (SiO2)
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
Fossilized Coral
Cnidaria (Anthozoa), often replaced by Calcium Carbonate (CaCO3) or Silica (SiO2)
Chert (specifically as a lithic artifact/projectile point)
Chert (Silicon dioxide, SiO2)
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
Amber
Fossilized Tree Resin (Generic formula roughly C10H16O)
Amber
Fossilized Tree Resin (Succinite for Baltic varieties)
Chert (River Pebble)
Silicon Dioxide (SiO2)
Travertine (Tufa)
Chemical Limestone (CaCO3)
Banded Agate (specifically Moss Agate or Plume Agate variety)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
Fossilized Shark Tooth (Fragment)
Elasmobranchii gen. indet.
Coal
Bituminous Coal / Anthracite
Petrified Wood
Silicified wood (primarily SiO2)
Petrified Wood
Silicified wood (primarily Silicon Dioxide, SiO2)
Oak Wood (Wood Grain Pattern)
Quercus (genus)
Shale
Fissile mudrock (composed primarily of clay minerals and quartz)
Chert
Chert (Silica: SiO2)
Fossil Coral
Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)
Fossil Coral (Honeycomb Coral)
Favosites (extinct genus of Tabulate coral)
Chert (Gravel pebble)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartzite
Quartzite (primarily SiO2)
Petrified Wood
Silicified Wood (SiO2)
Slate
Slate (foliated metamorphic rock, primarily composed of quartz, illite, chlorite, and micas)
Petrified Wood
Silicified Wood (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Pearl
Organic gemstone (Calcium carbonate / CaCO3 + Conchiolin)
Fossiliferous limestone (likely ammonite/gastropod-bearing)
Bioclastic limestone; predominantly calcite (CaCO₃)
Fossil bivalve shell
Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features
Calcite crystal
Calcite (calcium carbonate, CaCO₃)
Dyed Agate (Tumbled)
Silicon Dioxide (Chalcedony variety, artificially dyed)
Quartzite Pebble with Pyrite Coating
SiO2 (Quartz) with FeS2 (Pyrite) inclusions or surface coating
Amber
Fossilized Tree Resin (Successite)
Chert (Black Flint)
Microcrystalline Quartz (SiO2)
Fossiliferous Limestone
Limestone (CaCO3 - Calcium Carbonate)
Dendritic Agate (Tree Agate)
Chalcedony (Silicon Dioxide, SiO2) with Manganese or Iron Oxide inclusions
Amber
Succinite (C10H16O)
Pyrite in Shale
Iron Disulfide (FeS2) in Argillaceous Shale
Basaltic Tuff / Volcanic Breccia
Pyroclastic Breccia / Lithic Tuff
Shale (or Mudstone)
Siltstone/Argillite (composed mainly of clay and silt-sized particles)