Rock Identifier

Category

Organic (Geological Relative)

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

Quartz Geode (Silicon Dioxide (SiO2)) — sedimentary

Quartz Geode

Silicon Dioxide (SiO2)

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

Petrified Wood

Silicified wood (Quartz/Chalcedony/SiO2)

Fossilized ammonite fragment (Ammonoidea; likely an ammonite suture-section specimen, commonly Jurassic–Cretaceous) — fossil

Fossilized ammonite fragment

Ammonoidea; likely an ammonite suture-section specimen, commonly Jurassic–Cretaceous

Pyritic Mudstone (Argillaceous rock (FeS2)) — sedimentary

Pyritic Mudstone

Argillaceous rock (FeS2)

Petrified Wood (Silicified wood (primarily Silicon Dioxide, SiO2)) — sedimentary

Petrified Wood

Silicified wood (primarily Silicon Dioxide, SiO2)

Fossiliferous Shale Matrix (Clastic Sedimentary Rock with Brachiopod or Mollusk shell fragments) — sedimentary

Fossiliferous Shale Matrix

Clastic Sedimentary Rock with Brachiopod or Mollusk shell fragments

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

Petrified Wood

Silicified Wood (primarily SiO2)

Pyrite in Shale (Iron Sulfide (FeS2) in Argillaceous Shale) — sedimentary

Pyrite in Shale

Iron Sulfide (FeS2) in Argillaceous Shale

Pearls (Pearl: biomineralized aragonite (CaCO₃) and conchiolin) — gemstone

Pearls

Pearl: biomineralized aragonite (CaCO₃) and conchiolin

Polished orbicular jasper (Siliceous microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and other mineral inclusions) — sedimentary

Polished orbicular jasper

Siliceous microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and other mineral inclusions

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

Quartz Geode (Silicon Dioxide (SiO2)) — sedimentary

Quartz Geode

Silicon Dioxide (SiO2)

Graphite (Graphite (Native Carbon, C)) — metamorphic

Graphite

Graphite (Native Carbon, C)

Chert (Cherty Flint/Jasper variety) (Microcrystalline or cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (Cherty Flint/Jasper variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

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

Chert (Nodule)

Silicon Dioxide (SiO2)

Small seashell fossil or shell fragment (Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate) — fossil

Small seashell fossil or shell fragment

Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate

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

Chert (Chert Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Graphite (Graphite (C)) — mineral

Graphite

Graphite (C)

Chert (Arrowhead/Tool variety) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Arrowhead/Tool variety)

Microcrystalline Quartz (SiO2)

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

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Chert (Brown variety / Common Jasper) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Brown variety / Common Jasper)

Microcrystalline Quartz (SiO2)

Fossilized Shark Tooth (Chondrichthyes tooth) — fossil

Fossilized Shark Tooth

Chondrichthyes tooth

Chert (often called Flint or Jasper locally) (Chert (Microcrystalline Quartz, Formula: SiO2)) — sedimentary

Chert (often called Flint or Jasper locally)

Chert (Microcrystalline Quartz, Formula: SiO2)

Petrified Wood (Silicified wood (principally Silicon Dioxide, SiO2)) — sedimentary

Petrified Wood

Silicified wood (principally Silicon Dioxide, SiO2)

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

Chert (Flint Nodules)

Microcrystalline Quartz (SiO2)

Rose Quartz (Quartz (SiO₂), specifically a variety of Quartz) — Mineral

Rose Quartz

Quartz (SiO₂), specifically a variety of Quartz

Petrified Wood (Silicified Wood (SiO2)) — metamorphic

Petrified Wood

Silicified Wood (SiO2)

Dark Igneous Rock (Likely Basalt or Diabase) (Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.) — Igneous

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

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

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

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

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

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

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Rounded brown sandstone or weathered river cobble (Likely quartz-rich sandstone; exact identification requires a fresh surface and tests) — sedimentary

Rounded brown sandstone or weathered river cobble

Likely quartz-rich sandstone; exact identification requires a fresh surface and tests

Limestone with Lichen/Moss (Calcium Carbonate (CaCO3)) — sedimentary

Limestone with Lichen/Moss

Calcium Carbonate (CaCO3)

Concretion (likely iron-rich sandstone or claystone concretion) (Diagenetic carbonate/iron-oxide concretion; exact mineralogy requires testing) — sedimentary

Concretion (likely iron-rich sandstone or claystone concretion)

Diagenetic carbonate/iron-oxide concretion; exact mineralogy requires testing

Amber (Succinite (C10H16O)) — gemstone

Amber

Succinite (C10H16O)

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

Petrified Wood

Silicified Wood (primarily SiO2)

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

Petrified Wood

Silicified Wood (primarily SiO2)

Liesegang Ring Siltstone (Siltstone with iron oxide Liesegang bands) — sedimentary

Liesegang Ring Siltstone

Siltstone with iron oxide Liesegang bands

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

Moss Agate

Silicon Dioxide with inclusions (SiO2)

Chert (Arrowhead variety) (Chert (SiO2)) — sedimentary

Chert (Arrowhead variety)

Chert (SiO2)

Fossilized coral or silicified organic limestone (Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination) — fossil

Fossilized coral or silicified organic limestone

Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination

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

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)