Coral Fossil (Scleractinia)
Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)
Category
Browse organic (non geological) specimens identified by the Rock Identifier community.
Coral Fossil (Scleractinia)
Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)
Chert (specifically Jasper/Flint)
Microcrystalline Quartz (SiO2)
Chert (and Jasper/Chalcedony variety)
Microcrystalline Quartz (SiO2)
Chert (Nodule)
Silicon Dioxide (SiO2)
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Tufa Rock and Tumbled Gemstones
Calcareous Tufa (Calcium Carbonate, CaCO3)
Baltic Amber (Butterscotch variety)
Succinite
Manganese Dendrite on Siltstone
Manganese Oxide (pyrolusite or psilomelane) Dendrites
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
Black Obsidian
Volcanic Glass (70–75% SiO2 plus MgO, Fe3O4)
Shale or Argillite
Shale (fine-grained clastic sedimentary rock) or Argillite (low-grade metamorphic rock derived from shale)
Slag Glass
Vitreous Silicate Residue
Anthracite Coal
Anthracite (Carbon-based organic sedimentary rock exposed to metamorphic heat/pressure; Chemical composition is approximately 86%–98% Carbon)
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Chert / Flint
Silicon Dioxide (SiO2)
Chert / Flint
Microcrystalline Quartz (SiO2)
Chert (Jasper)
Cryptocrystalline Quartz (SiO2)
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
Green Jasper
Microcrystalline Quartz (Chalcedony), SiO2
Pyrite
Iron Disulfide (FeS2)
Pearl
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
Chert (Jasper variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Pyrite
Iron Disulfide (FeS2)
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide , SiO2)
Opalite
Man-made Opalized Glass (Synthetic Glass)
Gold
Native Gold (Au)
Sandstone with Liesegang Rings
Liesegang-banded Sandstone
White quartzite pebble (tentative)
Quartzite; predominantly microcrystalline quartz (SiO₂)
Possible fossilized bone fragment
Indeterminate vertebrate bone; no taxonomic identification is possible from the image alone
Quartzite
Quartzite (primarily SiO2)
Slag Glass (Cullet)
Amorphous Silicon Dioxide (SiO2) with metal oxide colorants
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Volcanic Glass (SiO2 + impurities)
Petrified Wood
Siliconized Wood (SiO2)
Glauconite (Greensand)
Glauconite (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2
Slag (Industrial Glass)
Artificial Vitreous Silicate
Jasper
Microcrystalline Quartz (SiO2)
Amber-like resin specimen
Likely amber (fossilized tree resin), commonly succinite; exact identification is uncertain from the image
Gold Ore in Matrix
Native Gold (Au) in Quartz/Limonite host rock
Flint with Fossil Inclusion
Cryptocrystalline quartz (SiO2) enclosing fossilized organic remains
Glass Nugget (Tumbled Glass)
Amorphous Silicon Dioxide (SiO2) with additives
Limestone
Calcium Carbonate (CaCO3)