Rock Identifier

Category

Organic (Often Found By Beachcombers)

Browse organic (often found by beachcombers) specimens identified by the Rock Identifier community.

Chert (often called Flint or Jasper) (Cryptocrystalline quartz (SiO2)) — sedimentary

Chert (often called Flint or Jasper)

Cryptocrystalline quartz (SiO2)

Chert (often called Flint) (Chert (Microcrystalline Quartz, SiO2)) — sedimentary

Chert (often called Flint)

Chert (Microcrystalline Quartz, SiO2)

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

Chert (Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Chert (Common Opal/Jasper variety) (Microcrystalline Quartz (SiO2) with hydration) — sedimentary

Chert (Common Opal/Jasper variety)

Microcrystalline Quartz (SiO2) with hydration

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

Chert (Nodule)

Silicon Dioxide (SiO2)

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

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and organic impurities

Brown Jasper (Likely) (Jasper (Cryptocrystalline Silicon Dioxide - SiO2)) — Mineral

Brown Jasper (Likely)

Jasper (Cryptocrystalline Silicon Dioxide - SiO2)

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

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Chert (Field Stone) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (Field Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Yellow Jasper (Iron-stained Chert) (Silicon Dioxide (SiO2) with iron oxide (Limonite/Goethite) inclusions) — sedimentary

Yellow Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with iron oxide (Limonite/Goethite) inclusions

Chert (variously identified as Flint) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (variously identified as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

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

Petrified Wood

Silicified Wood (SiO2 - Silicon Dioxide)

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

Ironstone Concretion (Iron-rich Mudstone)

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

Chert (Beach Pebble) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Beach Pebble)

Silicon Dioxide (SiO2)

Dendritic Agate (or Dendritic Opal) (SiO2 (for Agate), SiO2·nH2O (for Opal)) — Mineral

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Black Marble (Recrystallized Limestone (CaCO3)) — metamorphic

Black Marble

Recrystallized Limestone (CaCO3)

Stromatolite (Fossiliferous Limestone) (Biogenic Limestone (Calcium Carbonate, CaCO3)) — sedimentary

Stromatolite (Fossiliferous Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Basaltic Tuff / Volcanic Breccia (Pyroclastic Breccia / Lithic Tuff) — igneous

Basaltic Tuff / Volcanic Breccia

Pyroclastic Breccia / Lithic Tuff

River Stone (likely Mudstone or Siltstone) (Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)) — sedimentary

River Stone (likely Mudstone or Siltstone)

Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)

Chert (often called Jasper in this color variety) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (often called Jasper in this color variety)

Microcrystalline Quartz (SiO2)

Jasper (Petrified Wood variant) (Silicon Dioxide (SiO2) - Microcrystalline Quartz) — sedimentary

Jasper (Petrified Wood variant)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (Flint Pebbles) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Septarian Nodule (Dragon Stone) (Septarian concretion (composition: CaCO3 - Calcite, Aragonite, and Siderite/Limestone)) — sedimentary

Septarian Nodule (Dragon Stone)

Septarian concretion (composition: CaCO3 - Calcite, Aragonite, and Siderite/Limestone)

Shale with Vein Infillings (Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.) — Sedimentary Rock

Shale with Vein Infillings

Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.

Sedimentary Rock

Fossilized Wood (with Coal and Limonite) (Petrified Wood (Silicified or Carbonized Flora)) — sedimentary

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Chert (Quartz Pebble) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Quartz Pebble)

Silicon Dioxide (SiO2)

Pearl (Calcium Carbonate (CaCO3) with Conchiolin) — mineral

Pearl

Calcium Carbonate (CaCO3) with Conchiolin

Chert (often called Flint) (Microcrystalline or cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (often called Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Limestone with Quartz/Calcite Veins (Sedimentary Limestone (CaCO3 with SiO2 or CaCO3 intrusions)) — sedimentary

Limestone with Quartz/Calcite Veins

Sedimentary Limestone (CaCO3 with SiO2 or CaCO3 intrusions)

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

Chert (and/or Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Jasper (specifically Yellow Jasper and Red Jasper) (Silicon Dioxide (SiO2) with iron oxide inclusions) — sedimentary

Jasper (specifically Yellow Jasper and Red Jasper)

Silicon Dioxide (SiO2) with iron oxide inclusions

Banded Chert (Ironstone/Jasper) (Cryptocrystalline Quartz (SiO2) with Iron Oxides) — sedimentary

Banded Chert (Ironstone/Jasper)

Cryptocrystalline Quartz (SiO2) with Iron Oxides

Pearl (Calcium carbonate (CaCO3) as Aragonite or Calcite) — mineral

Pearl

Calcium carbonate (CaCO3) as Aragonite or Calcite

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

Petrified Wood

Silicified Wood (primarily SiO2)

Amber (Succinite (Fossilized Tree Resin)) — mineraloid

Amber

Succinite (Fossilized Tree Resin)

Chert (within Asphalt) (Chert (SiO2)) — sedimentary

Chert (within Asphalt)

Chert (SiO2)

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

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Septarian Nodule (Septarian Concretion) — sedimentary

Septarian Nodule

Septarian Concretion

Amber (Rough) (Amber (Fossilized Tree Resin, succinite)) — mineral

Amber (Rough)

Amber (Fossilized Tree Resin, succinite)

Pink Opal (Common Opal) (Amorphous Hydrated Silica (SiO2·nH2O)) — mineral

Pink Opal (Common Opal)

Amorphous Hydrated Silica (SiO2·nH2O)

Ambergris (Geological/Organic Specimen) (Ambra grisea (Produced by Physeter macrocephalus)) — organic material

Ambergris (Geological/Organic Specimen)

Ambra grisea (Produced by Physeter macrocephalus)

organic material

Ironstone Concretion (Limonite/Hematite Nodules) (Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)) — sedimentary

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)