Rock Identifier

Category

Organic (Geological Relative)

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

Pink shell fragment (Calcium carbonate, likely aragonite or calcite (CaCO₃); probably a bivalve or gastropod shell fragment) — fossil

Pink shell fragment

Calcium carbonate, likely aragonite or calcite (CaCO₃); probably a bivalve or gastropod shell fragment

Chert (Pink Jasper) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Pink Jasper)

Microcrystalline Quartz (SiO2)

Chert (Flint) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

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

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Mudstone variety with Oxidation) (Silicon dioxide (SiO2)) — sedimentary

Chert (Jasper/Mudstone variety with Oxidation)

Silicon dioxide (SiO2)

Jasper (Silicon Dioxide (SiO2) with iron oxide impurities) — sedimentary

Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Glauconite sand (Glauconite (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2) — sedimentary

Glauconite sand

Glauconite (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2

Petrified Wood (Silicified Wood (primarily Quartz/Chalcedony, formula: SiO2)) — sedimentary

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula: SiO2)

Orange Calcite (Calcium Carbonate (CaCO3)) — mineral

Orange Calcite

Calcium Carbonate (CaCO3)

Limestone (or Sandstone) (Calcium Carbonate (CaCO3) / Silica (SiO2)) — sedimentary

Limestone (or Sandstone)

Calcium Carbonate (CaCO3) / Silica (SiO2)

Pearl (Aragonite / Calcium Carbonate (CaCO3)) — mineral

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Petrified Wood (Silicified Wood (SiO2)) — metamorphic

Petrified Wood

Silicified Wood (SiO2)

Moss Agate (Chalcedony (Silicon Dioxide, SiO2) with inclusions) — mineral

Moss Agate

Chalcedony (Silicon Dioxide, SiO2) with inclusions

Glauconitic Sandstone (Greensand) (Glauconitic quartz wacke or arenite) — sedimentary

Glauconitic Sandstone (Greensand)

Glauconitic quartz wacke or arenite

Coral Fossil (Agatized Coral or Petoskey Stone) (Hexagonaria percarinata (if Petoskey) or generally Scleractinia (Agatized Coral)) — Sedimentary/Fossil

Coral Fossil (Agatized Coral or Petoskey Stone)

Hexagonaria percarinata (if Petoskey) or generally Scleractinia (Agatized Coral)

Sedimentary/Fossil

Petrified Wood (Silicified Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood (SiO2)

Coal (most likely Bituminous or Anthracite) (Coal (organic sedimentary rock)) — Sedimentary

Coal (most likely Bituminous or Anthracite)

Coal (organic sedimentary rock)

Petrified Wood (Silicified Wood (SiO2)) — mineral

Petrified Wood

Silicified Wood (SiO2)

Fossilized Fish Skeleton in Matrix (Vertebrata (Class: Actinopterygii), typically found in limestone or shale matrices) — sedimentary

Fossilized Fish Skeleton in Matrix

Vertebrata (Class: Actinopterygii), typically found in limestone or shale matrices

Geode with Quartz Crystal Cavity (Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix) — sedimentary

Geode with Quartz Crystal Cavity

Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix

Limestone Concretion (Botryoidal/Calcareous Nodules) (Calcium Carbonate Concretion (CaCO3)) — sedimentary

Limestone Concretion (Botryoidal/Calcareous Nodules)

Calcium Carbonate Concretion (CaCO3)

Glauconitic Sandstone (Glauconitic Quartz Arenite) — sedimentary

Glauconitic Sandstone

Glauconitic Quartz Arenite

Septarian Nodule (Micro-fragment) (Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)) — sedimentary

Septarian Nodule (Micro-fragment)

Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)

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

Petrified Wood

Silicified Wood (primarily SiO2)

Banded Chert with Quartz Veining (Microcrystalline Quartz (SiO2)) — sedimentary

Banded Chert with Quartz Veining

Microcrystalline Quartz (SiO2)

Pyrite in Slate (Iron Sulfide (FeS2) in Slate host matrix) — metamorphic

Pyrite in Slate

Iron Sulfide (FeS2) in Slate host matrix

Pearl (Nacre (aragonite, CaCO₃, in a conchiolin matrix)) — gemstone

Pearl

Nacre (aragonite, CaCO₃, in a conchiolin matrix)

Calcite (Calcite (CaCO
3)) — Mineral

Calcite

Calcite (CaCO 3)

Rounded brown chert (flint) pebble (Microcrystalline quartz (SiO₂), commonly with iron-oxide staining) — sedimentary

Rounded brown chert (flint) pebble

Microcrystalline quartz (SiO₂), commonly with iron-oxide staining

Cultured pearls (Pearl; predominantly aragonite (CaCO₃) in nacre with organic conchiolin) — gemstone

Cultured pearls

Pearl; predominantly aragonite (CaCO₃) in nacre with organic conchiolin

Dendritic jasper/chalcedony (Silica-rich microcrystalline quartz (SiO₂) with manganese-oxide dendrites) — mineral

Dendritic jasper/chalcedony

Silica-rich microcrystalline quartz (SiO₂) with manganese-oxide dendrites

Tumbled moss agate (Chalcedony (microcrystalline quartz, SiO₂) with moss-like inclusions) — mineral

Tumbled moss agate

Chalcedony (microcrystalline quartz, SiO₂) with moss-like inclusions

Chert (varieties: Flint or Chalcedony) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (varieties: Flint or Chalcedony)

Microcrystalline Quartz (SiO2)

Glendonite (Calcite Pseudomorph after Ikaite) (Calcite (CaCO3) pseudomorph after Ikaite (CaCO3·6H2O)) — mineral

Glendonite (Calcite Pseudomorph after Ikaite)

Calcite (CaCO3) pseudomorph after Ikaite (CaCO3·6H2O)

Banded agate (likely petrified wood or silicified sediment) (Microcrystalline quartz/chalcedony, SiO₂; possible silicified wood) — sedimentary

Banded agate (likely petrified wood or silicified sediment)

Microcrystalline quartz/chalcedony, SiO₂; possible silicified wood

Yellow calcite crystal specimen (Calcite (CaCO₃), likely honey/yellow calcite) — mineral

Yellow calcite crystal specimen

Calcite (CaCO₃), likely honey/yellow calcite

Botryoidal pyrite (likely with quartz or chlorite matrix) (Pyrite, FeS₂; botryoidal aggregate) — mineral

Botryoidal pyrite (likely with quartz or chlorite matrix)

Pyrite, FeS₂; botryoidal aggregate

Jasper (Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)) — sedimentary

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Chert (Flint) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (and/or Flint) (Microcrystalline or cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (and/or Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (variant Flint) (Silicon Dioxide (SiO2)) — sedimentary

Chert (variant Flint)

Silicon Dioxide (SiO2)

Sandstone (Arenite (primarily composed of SiO2)) — sedimentary

Sandstone

Arenite (primarily composed of SiO2)