Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxide
mineral
Category
Organic (Often Found By Beachcombers)
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Chert (and Jasper/Flint variety)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (variations include Flint or Jasper)
Aphanitic Silica (SiO2)
sedimentary
Ambergris
Ambergris (Coprolite-adjacent/Organic secretion)
mineraloid
Banded Chert / Banded Jasper (likely a variety of Chert/Chalcedony)
Chert (microcrystalline quartz)
Metamorphic Rock
Ambergris
Ambra grisea (Metabolic byproduct)
Organic (Geological relative)
Amber
Succinite (approximate formula C10H16O)
mineraloid
Chert (Gravel)
Microcrystalline silica (SiO2)
sedimentary
Chert (Jasper)
Microcrystalline quartz (SiO2)
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide
mineral
Chert (and Flint)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (and Flint)
Silicon Dioxide (SiO2)
sedimentary
Chalcedony Geode
Chalcedony (SiO2) within a geode structure
Mineral Geode/Sedimentary or Volcanic related
Chert
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Red Coral
Corallium rubrum
mineral
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Smooth River Siltstone/Basalt variant)
Silicon dioxide (SiO2) / Microcrystalline Quartz
sedimentary
Coral Fossil (Scleractinia)
Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)
sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with Bioclasts
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert (Green variety)
Silicon Dioxide (SiO2)
sedimentary
Amber
Succinite (specifically for Baltic amber); Chemical formula approximately C10H16O
mineral
Amber
Succinite (specifically for Baltic amber); Complex mixture of organic compounds (C10H16O)
Organic Mineraloid
Pearl
Calcium Carbonate (Aragonite or Calcite) and Conchiolin
Mineraloid
Red Jasper
Red Jasper (variety of Chalcedony, SiO₂)
Mineral
Petrified Wood
Silicified wood (primarily Silicon Dioxide, SiO2)
metamorphic
Pearl and Garnet Glass
Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass
mineral and glass
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Iron-rich)
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
sedimentary
Chert (and Flint)
Silicon dioxide (SiO2) - Microcrystalline or Cryptocrystalline Quartz
sedimentary
Chert (and Jasper pebble)
Microcrystalline Silica (SiO2)
sedimentary
Shale or Mudstone (Based on appearance)
Shale (fine-grained, laminated fissile sedimentary rock) / Mudstone (fine-grained, non-fissile sedimentary rock)
Sedimentary
Sandstone with Vitrinite/Coal inclusions
Arenite with Carbonaceous inclusions
sedimentary
Fossiliferous Limestone
Carbonate sedimentary rock (CaCO3) with bioclasts
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Mother of Pearl (Nacre)
Aragonite (layered with organic polymers), CaCO3
mineral
Petrified Wood
Silicified wood (primarily SiO2)
sedimentary
Chert / Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Shark Tooth Fossil
Carcharodonta (order Lamniformes), likely Carcharias spp.
fossil