Ironstone Concretion (Limonite/Goethite)
Iron oxide concretion (contains FeO(OH)·nH2O)
sedimentary
Category
Organic (Often Found By Beachcombers)
Browse organic (often found by beachcombers) specimens identified by the Rock Identifier community.
Petrified Wood
Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)
sedimentary
Fossil Shell (Bivalve)
Phylum Mollusca, Class Bivalvia (typically composed of Calcium Carbonate / CaCO3)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Chert (and/or Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (specifically Pink Chert or Jasperized Chert)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Amber / Copal
Fossilized Tree Resin (Succinate)
Mineraloid
Chert (Flint variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper variety)
Chert (SiO2)
sedimentary
Chert (varietal Chalcedony or Flint)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (specifically Banded Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Aragonite (Star Cluster or Twinned variety)
Aragonite (Calcium Carbonate, CaCO3)
mineral
Chert (Flint)
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Chert (Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Cherty Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Sandstone (Weathered Coastal Boulder)
Arenite (composed primarily of SiO2)
sedimentary
Pyrite in Shale
Iron Disulfide (FeS2) in Argillaceous Shale
sedimentary
Chert Pebble
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicon Dioxide (SiO2) - Calcified / Silicified Wood
sedimentary
Chert (Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Fossiliferous Limestone (with Crinoids)
CaCO3 (Calcium Carbonate)
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Amber
Succinite (specific to Baltic amber), fossilized tree resin
Organic Mineraloid
Chert (Nodule)
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Chert (specifically Flint Arrowhead)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (and its variety Flint)
Silicon dioxide (SiO2) / Microcrystalline quartz
sedimentary
Black Jasper
Black Jasper (Silicate mineral - SiO2)
sedimentary
Amber
Succinicum (Succinite); C10H16O
Mineraloid (Organic)
Pink Opal
Hydrated Amorphous Silica (SiO2·nH2O)
mineraloid
Red Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Chert (specifically Red Chert/Jasper nodule)
Microcrystalline Quartz (SiO2)
sedimentary
Red Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (Black Chert / Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline quartz (SiO2)
sedimentary
Black Pearl (Tahitian-style Cultured Pearl)
Calcium Carbonate (Aragonite) with Conchiolin (CaCO3)
mineral
Petrified Wood
Silicified Wood (SiO2 permineralization)
sedimentary
Mixed Quartz and Jasper Pebbles
Silicon Dioxide (SiO2)
Mineral
Chert (Black Chert/Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Ambergris
Ambergris (Coprolite-adjacent organic substance)
Organic (Geological interest)