Rock Identifier

Category

Organic Crystal (Mineraloid)

Browse organic crystal (mineraloid) specimens identified by the Rock Identifier community.

Anthracite Coal (Anthracite (Carbon-based organic sedimentary/metamorphic rock)) — metamorphic

Anthracite Coal

Anthracite (Carbon-based organic sedimentary/metamorphic rock)

Dyed Blue Agate (Dragon Vein Agate) (Silicon Dioxide (SiO2) with artificial cobalt/organic dyes) — mineral

Dyed Blue Agate (Dragon Vein Agate)

Silicon Dioxide (SiO2) with artificial cobalt/organic dyes

Petrified Wood (Silicified Wood (SiO2 - Silicon Dioxide)) — mineral

Petrified Wood

Silicified Wood (SiO2 - Silicon Dioxide)

Massive Cryptocrystalline Quartz (Chert/Chalcedony Pebble) (Silicon Dioxide (SiO2)) — sedimentary

Massive Cryptocrystalline Quartz (Chert/Chalcedony Pebble)

Silicon Dioxide (SiO2)

Coal (Anthracite) (Anthracite (Carbon-based organic sedimentary/metamorphic rock)) — metamorphic

Coal (Anthracite)

Anthracite (Carbon-based organic sedimentary/metamorphic rock)

Petrified Wood (Silicified Wood (SiO2)) — fossil

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood (Silicified wood (Quartz / Chalcedony replacement of organic cellulose)) — fossil

Petrified Wood

Silicified wood (Quartz / Chalcedony replacement of organic cellulose)

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

Red Jasper

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

Septarian Nodule (Septarian Concretion (Calcite, Aragonite, and Limestone)) — sedimentary

Septarian Nodule

Septarian Concretion (Calcite, Aragonite, and Limestone)

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

Petrified Wood

Silicified wood (primarily Silicon Dioxide - SiO2)

Chert (specifically Jasper or Flint) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (specifically Jasper or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

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

Moss Agate

Chalcedony (Silicon Dioxide with inclusions) - SiO2

Coal (Bituminous) (Organic sedimentary rock primarily consisting of carbon (C)) — sedimentary

Coal (Bituminous)

Organic sedimentary rock primarily consisting of carbon (C)

Chert (Grey-Green Var.) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Grey-Green Var.)

Silicon Dioxide (SiO2)

Dendritic Opal (Common Opal) (Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions) — mineral

Dendritic Opal (Common Opal)

Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions

Shale (Shale (fine-grained clastic sedimentary rock)) — Sedimentary

Shale

Shale (fine-grained clastic sedimentary rock)

Petrified Wood (Silicified wood (primarily quartz replacing organic cellulose)) — fossil

Petrified Wood

Silicified wood (primarily quartz replacing organic cellulose)

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

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and organic impurities

Petrified Wood (Silicified Wood (SiO2)) — fossil

Petrified Wood

Silicified Wood (SiO2)

Chert (varietal: Jasper or Flint likely, but definitive identification is difficult from image) (SiO₂ (silicon dioxide)) — Sedimentary

Chert (varietal: Jasper or Flint likely, but definitive identification is difficult from image)

SiO₂ (silicon dioxide)

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

Travertine (Tufa)

Calcium Carbonate (CaCO3)

Anthracite Coal (Anthracite (Carbon-rich metamorphic coal)) — metamorphic

Anthracite Coal

Anthracite (Carbon-rich metamorphic coal)

Flint (Chert (Cryptocrystalline Quartz, SiO2)) — sedimentary

Flint

Chert (Cryptocrystalline Quartz, SiO2)

Red Sandstone with Reduction Spot (Quartzose Sandstone with a Leach/Reduction Spot) — sedimentary

Red Sandstone with Reduction Spot

Quartzose Sandstone with a Leach/Reduction Spot

Graphite (Graphite (C)) — mineral

Graphite

Graphite (C)

Septarian Nodule (Dragon Stone) (Septarian Geode (CaCO3 + Mg + Fe)) — sedimentary

Septarian Nodule (Dragon Stone)

Septarian Geode (CaCO3 + Mg + Fe)

Banded sandstone pebble (Quartz-rich lithic sandstone; exact provenance and composition require testing) — sedimentary

Banded sandstone pebble

Quartz-rich lithic sandstone; exact provenance and composition require testing

Petrified Wood (Silicified Wood (primarily Chalcedony/Quartz, SiO2)) — fossil

Petrified Wood

Silicified Wood (primarily Chalcedony/Quartz, SiO2)

Moss Agate (Silicon Dioxide with inclusions (SiO2 + impurities)) — mineral

Moss Agate

Silicon Dioxide with inclusions (SiO2 + impurities)

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

Septarian Nodule (Dragon Stone)

Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)

Petrified Wood (Silicified wood (SiO2)) — sedimentary

Petrified Wood

Silicified wood (SiO2)

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

Petrified Wood

Silicified Wood (primarily SiO₂ - Silicon Dioxide)

Petrified Wood (Silicified Wood (SiO2)) — fossil

Petrified Wood

Silicified Wood (SiO2)

Green Jasper (Silicon Dioxide (SiO2) with impurities) — sedimentary

Green Jasper

Silicon Dioxide (SiO2) with impurities

Ironstone Concretion / Limonite Node (Ferruginous Sedimentary Rock (composed primarily of Limonite FeO(OH)·nH2O and Goethite)) — sedimentary

Ironstone Concretion / Limonite Node

Ferruginous Sedimentary Rock (composed primarily of Limonite FeO(OH)·nH2O and Goethite)

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

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)

Septarian Nodule (Septarian Concretion (Calcite, Aragonite, and Limestone)) — sedimentary

Septarian Nodule

Septarian Concretion (Calcite, Aragonite, and Limestone)

Petrified Wood (Silicified Wood (SiO2)) — fossil

Petrified Wood

Silicified Wood (SiO2)

Pink Opal / Peruvian Opal (Hydrated amorphous silicon dioxide (SiO2·nH2O)) — Mineral

Pink Opal / Peruvian Opal

Hydrated amorphous silicon dioxide (SiO2·nH2O)

Chert (specifically Tan/Yellow Chert) (Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)) — sedimentary

Chert (specifically Tan/Yellow Chert)

Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)

Petrified Wood (Silicified Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood (SiO2)

Chert (Quartz Variety) (Microcrystalline Silica (SiO2)) — sedimentary

Chert (Quartz Variety)

Microcrystalline Silica (SiO2)