Rock Identifier

Category

Organic (Pseudo Geological)

Browse organic (pseudo geological) specimens identified by the Rock Identifier community.

Coquina / Shelly Sandstone (Calcareous Sandstone / Coquina) — sedimentary

Coquina / Shelly Sandstone

Calcareous Sandstone / Coquina

Limestone (Calcium Carbonate (CaCO3)) — sedimentary

Limestone

Calcium Carbonate (CaCO3)

Red coral earrings (Corallium rubrum or related precious coral (calcareous coral skeleton; primarily aragonite, CaCO₃)) — gemstone

Red coral earrings

Corallium rubrum or related precious coral (calcareous coral skeleton; primarily aragonite, CaCO₃)

Septarian Nodule (Septarian Concretion (CaCO3 with Siderite/Calcite/Aragonite)) — sedimentary

Septarian Nodule

Septarian Concretion (CaCO3 with Siderite/Calcite/Aragonite)

Fossiliferous limestone pebble (probable coral or shell fossil) (Calcite (CaCO₃), commonly biogenic limestone; exact fossil taxon indeterminate from the image) — fossil

Fossiliferous limestone pebble (probable coral or shell fossil)

Calcite (CaCO₃), commonly biogenic limestone; exact fossil taxon indeterminate from the image

Amber (Succinite (Carbon-based organic compound; approximate formula C10H16O)) — Mineraloid

Amber

Succinite (Carbon-based organic compound; approximate formula C10H16O)

Honey calcite (calcareous mineral specimen) (Calcite, CaCO₃; likely honey/yellow calcite with minor iron-oxide staining) — mineral

Honey calcite (calcareous mineral specimen)

Calcite, CaCO₃; likely honey/yellow calcite with minor iron-oxide staining

Chert (often called Flint when found in chalk/limestone) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (often called Flint when found in chalk/limestone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Blue-gray limestone or marble fragment (Calcite-rich carbonate rock; likely calcitic marble (CaCO₃), though limestone is possible) — metamorphic

Blue-gray limestone or marble fragment

Calcite-rich carbonate rock; likely calcitic marble (CaCO₃), though limestone is possible

Ambergris (Marine Coprolite/Subfossil) (Marine organic coprolite / Ambergris (Physeter macrocephalus metabolite)) — fossil

Ambergris (Marine Coprolite/Subfossil)

Marine organic coprolite / Ambergris (Physeter macrocephalus metabolite)

Graphite-rich metamorphic rock (probable graphite schist) (Graphite schist; predominantly graphite (C) with quartz and mica) — metamorphic

Graphite-rich metamorphic rock (probable graphite schist)

Graphite schist; predominantly graphite (C) with quartz and mica

Travertine (Tufa) (Calcium Carbonate (CaCO3)) — sedimentary

Travertine (Tufa)

Calcium Carbonate (CaCO3)

Banded Chert (Microcrystalline silicon dioxide (SiO2)) — sedimentary

Banded Chert

Microcrystalline silicon dioxide (SiO2)

Ironstone Concretion (Siderite or Hematite Concretion) — sedimentary

Ironstone Concretion

Siderite or Hematite Concretion

Weathered iron-rich limestone or sandstone (Ferruginous carbonate/siliciclastic rock; likely calcite- and iron-oxide-bearing matrix) — sedimentary

Weathered iron-rich limestone or sandstone

Ferruginous carbonate/siliciclastic rock; likely calcite- and iron-oxide-bearing matrix

Fancy Jasper (Agate/Chert mix) (Silicon Dioxide (SiO2) with impurities) — sedimentary

Fancy Jasper (Agate/Chert mix)

Silicon Dioxide (SiO2) with impurities

Pearl (Nacre (aragonite, CaCO₃, with conchiolin)) — gemstone

Pearl

Nacre (aragonite, CaCO₃, with conchiolin)

Petrified Wood (Silicified wood (Quartz/Chalcedony - SiO2)) — sedimentary

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Petrified Wood (Silicified Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood (SiO2)

Amber (Succinite (specific to Baltic amber), fossilized tree resin) — mineraloid

Amber

Succinite (specific to Baltic amber), fossilized tree resin

Ironstone Concretion (Siderite or Goethite Concretion) — sedimentary

Ironstone Concretion

Siderite or Goethite Concretion

Travertine (often colloquially called Tufa) (Chemical Sedimentary Calcium Carbonate (CaCO3)) — sedimentary

Travertine (often colloquially called Tufa)

Chemical Sedimentary Calcium Carbonate (CaCO3)

Sandstone Pebble (River Rock) (Sandstone (Quartz-rich sedimentary rock with iron oxide staining)) — sedimentary

Sandstone Pebble (River Rock)

Sandstone (Quartz-rich sedimentary rock with iron oxide staining)

Petrified Wood (Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)) — metamorphic

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)

Septarian Nodule (Dragon Stone) (Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)) — sedimentary

Septarian Nodule (Dragon Stone)

Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)

Limestone (Calcium Carbonate (CaCO3)) — sedimentary

Limestone

Calcium Carbonate (CaCO3)

Jasper (Silicon Dioxide (Microcrystalline Quartz / Chalcedony)) — sedimentary

Jasper

Silicon Dioxide (Microcrystalline Quartz / Chalcedony)

Dalmatian jasper (often sold as Dalmatian stone) (Quartz-bearing leucocratic alkali-feldspar–aegirine/arfvedsonite porphyritic rock; commercial “jasper” designation) — igneous

Dalmatian jasper (often sold as Dalmatian stone)

Quartz-bearing leucocratic alkali-feldspar–aegirine/arfvedsonite porphyritic rock; commercial “jasper” designation

Chert (likely flint) (Microcrystalline quartz, SiO₂ (chalcedony-rich chert)) — sedimentary

Chert (likely flint)

Microcrystalline quartz, SiO₂ (chalcedony-rich chert)

Black Marble with Quartz Veining (Metamorphosed Limestone (Recrystallized CaCO3)) — metamorphic

Black Marble with Quartz Veining

Metamorphosed Limestone (Recrystallized CaCO3)

Water and Silt (Sedimentary Environment) (Suspended Sediment / H2O (dihydrogen monoxide)) — sedimentary

Water and Silt (Sedimentary Environment)

Suspended Sediment / H2O (dihydrogen monoxide)

Jasper (Agate/Jasper (Microcrystalline Quartz, SiO2)) — sedimentary

Jasper

Agate/Jasper (Microcrystalline Quartz, SiO2)

Petrified Wood (Silicified Wood (SiO2)) — mineral

Petrified Wood

Silicified Wood (SiO2)

Green Moss Agate (Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite) — sedimentary

Green Moss Agate

Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite

Red Sandstone (Arenite (Iron-rich Sandstone)) — sedimentary

Red Sandstone

Arenite (Iron-rich Sandstone)

Iron-rich sandstone or lateritic rock (Ferruginous sandstone; predominantly quartz (SiO₂) with iron oxides/hydroxides such as hematite and goethite) — sedimentary

Iron-rich sandstone or lateritic rock

Ferruginous sandstone; predominantly quartz (SiO₂) with iron oxides/hydroxides such as hematite and goethite

Chert with Calcite Veining (Microcrystalline Quartz (SiO2) with Calcium Carbonate (CaCO3) veins) — sedimentary

Chert with Calcite Veining

Microcrystalline Quartz (SiO2) with Calcium Carbonate (CaCO3) veins

Fossil crocodilian skull and jaws (Crocodyliform fossil; exact genus and species cannot be determined from the image) — fossil

Fossil crocodilian skull and jaws

Crocodyliform fossil; exact genus and species cannot be determined from the image

Aragonite crystal cluster (Aragonite, orthorhombic calcium carbonate (CaCO₃)) — mineral

Aragonite crystal cluster

Aragonite, orthorhombic calcium carbonate (CaCO₃)

Hardpan Nodule / Ferruginous Sandstone (Ferruginous Sandstone (Fe-cemented sediment)) — sedimentary

Hardpan Nodule / Ferruginous Sandstone

Ferruginous Sandstone (Fe-cemented sediment)

Sandstone (with carbonaceous plant fragments) (Arenite (composed primarily of SiO2)) — sedimentary

Sandstone (with carbonaceous plant fragments)

Arenite (composed primarily of SiO2)

Moss Agate (Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides) — Mineral (Variety of Chalcedony)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Mineral (Variety of Chalcedony)