Limestone
Calcareous sedimentary rock (CaCO3)
Category
Browse organic (anthropogenic) specimens identified by the Rock Identifier community.
Limestone
Calcareous sedimentary rock (CaCO3)
Limestone Boulder
Sedimentary Rock (Calcium Carbonate, CaCO3)
Petrified Wood
Silicified Wood (SiO2)
Red Jasper with Fossils
Silicified Fossiliferous Jasper (Chert variant, SiO2)
Honeycomb Coral Fossil
Favosites (extinct genus of tabulate coral)
Limestone
Calcium Carbonate (CaCO3)
Fossilized Coral (Petrified Coral)
Lithostrotionella (example genus) / Scleractinia
Amber
Succinite (fossilized resin)
Limestone
Calcium Carbonate (CaCO3)
Turquoise and Red Coral
Turquoise: CuAl6(PO4)4(OH)8·4H2O; Red Coral: Corallium rubrum (organic gemstone)
Black Onyx
Cryptocrystalline Quartz (SiO2 with organic/iron impurities)
Black Pearl (Tahitian or Irradiated Type)
Organic gemstone (Calcium Carbonate with Conchiolin Binding)
Blue Agate (Tumbled and Dyed)
Silicon Dioxide (SiO2) with likely organic dyes
Chert Nodule
Microcrystalline Quartz (SiO2)
Amber
Fossilized Tree Resin (C10H16O)
Freshwater Pearl
Calcium Carbonate (CaCO3) in the form of Aragonite and Calcite
Amber with Inclusion
Succiniferous fossil resin (C10H16O)
Amber
Succinate (Fossilized Tree Resin)
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
Moss Agate
Cryptocrystalline Quartz (SiO2 with Manganese or Iron Oxide inclusions)
Chert (specifically Blue Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Pink Opal (Common Opal)
Amorphous Hydrated Silica (SiO2·nH2O)
Plume Agate
Silicon Dioxide (SiO2) - Chalcedony Variety
Shale or Slaty Mudstone
Argillaceous sedimentary rock
Moss agate bracelet
Chalcedony (microcrystalline quartz, SiO₂) with chlorite/amphibole inclusions
Fossil gastropod shell
Fossilized marine gastropod; exact genus/species requires locality and examination
Tumbled chert or flint pebble
Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from the image
Chert Nodule in Limestone (Flint in Chalk)
SiO2 (Microcrystalline Quartz) in CaCO3 (Calcite)
Banded Agate (Dyed)
SiO2 (Silicon Dioxide / Microcrystalline Quartz)
Amber (Rough)
Succinite (Resinite)
Moss Agate
Silicon Dioxide (SiO2) with inclusions
Pink Opal
Hydrated Silica (SiO2·nH2O) with Palygorskite/Sepiolite inclusions
Petrified Wood
Silicified Wood (SiO2)
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide/Quartz)
Tufa (Limestone)
Calcareous Tufa (CaCO3)
Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxides
Gastropod Steinkern (Fossil Snail Internal Mold)
Class Gastropoda (Internal Mold)
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
Amber
Succinurite (C10H16O)
Amber Inlay Jewelry
Fossilized Resin (C10H16O)
Sandstone with Trace Fossils
Quartz Arenite with Bioturbation (Trace Fossils)
Limestone
Calcium Carbonate (CaCO3)