Rock Identifier

Category

Organic (Geological Interest)

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

Chert (Jasper variation) (Silicon Dioxide (SiO2) - Microcrystalline Quartz) — sedimentary

Chert (Jasper variation)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Fossilized Coral (Petoskey Stone or Tabulate Coral) (Scleractinia or Tabulata (CaCO3 - Calcium Carbonate)) — fossil

Fossilized Coral (Petoskey Stone or Tabulate Coral)

Scleractinia or Tabulata (CaCO3 - Calcium Carbonate)

Fossiliferous Limestone (Calcite-rich Sedimentary Rock (CaCO3)) — sedimentary

Fossiliferous Limestone

Calcite-rich Sedimentary Rock (CaCO3)

Travertine (Calcareous Tufa (CaCO3)) — sedimentary

Travertine

Calcareous Tufa (CaCO3)

Chert (Chert Nodule) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (Chert Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Iron-stained River Cobble) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Iron-stained River Cobble)

Microcrystalline Quartz (SiO2)

Graphite (Graphite (C)) — mineral

Graphite

Graphite (C)

Chert (Septarian or Nodular variety) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Septarian or Nodular variety)

Microcrystalline Quartz (SiO2)

Raw honey calcite (Calcite (calcium carbonate, CaCO₃)) — mineral

Raw honey calcite

Calcite (calcium carbonate, CaCO₃)

Fossiliferous limestone pebble (Micritic to bioclastic limestone, composed mainly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone pebble

Micritic to bioclastic limestone, composed mainly of calcite (CaCO₃)

Ironstone Concretion (Iron-rich Mudstone) (Siderite / Geothite concretion (FeCO3 / FeO(OH))) — sedimentary

Ironstone Concretion (Iron-rich Mudstone)

Siderite / Geothite concretion (FeCO3 / FeO(OH))

Limestone (Weathered) (Calcium Carbonate (CaCO3)) — sedimentary

Limestone (Weathered)

Calcium Carbonate (CaCO3)

Red Jasper (Silicon dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions) — sedimentary

Red Jasper

Silicon dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Petrified Wood (Silicified Wood (primarily SiO2)) — sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

Banded calcite (travertine or calcite-rich carbonate) (Calcite, CaCO₃; likely banded travertine or recrystallized limestone) — sedimentary

Banded calcite (travertine or calcite-rich carbonate)

Calcite, CaCO₃; likely banded travertine or recrystallized limestone

Chert (River Pebble) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Petrified Wood (Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)) — Mineral/Fossil (Sedimentary context)

Petrified Wood

Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)

Mineral/Fossil (Sedimentary context)

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

Coquina / Shelly Sandstone

Calcareous Sandstone / Coquina

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)

Limestone (Calcium Carbonate (CaCO3)) — sedimentary

Limestone

Calcium Carbonate (CaCO3)

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

Ambergris (Marine Coprolite/Subfossil)

Marine organic coprolite / Ambergris (Physeter macrocephalus metabolite)

Granite (Granite (a felsic intrusive igneous rock)) — Igneous rock

Granite

Granite (a felsic intrusive igneous rock)

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

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)

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

Amber

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

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

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)

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

Fossil Coral (Fossilized Scleractinia or Tabulata (various genera/species)) — Sedimentary

Fossil Coral

Fossilized Scleractinia or Tabulata (various genera/species)

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

Pearl

Nacre (aragonite, CaCO₃, with conchiolin)

Ironstone Concretion (Siderite or Hematite Concretion) — sedimentary

Ironstone Concretion

Siderite or Hematite Concretion

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

Fancy Jasper (Agate/Chert mix)

Silicon Dioxide (SiO2) with impurities

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

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

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 (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

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

Jasper

Silicon Dioxide (Microcrystalline Quartz / Chalcedony)