Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Category
Organic (Often Found By Beachcombers)
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Chert (containing Iron Oxide spots)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Dinosaur Skull (Tyrannosaurus rex)
Tyrannosaurus rex (permineralized fossil), rich in Hydroxylapatite/Silica
sedimentary
Amber
Succinite (Fossilized Tree Resin)
Organic Mineraloid
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with inclusions of Chlorite, Manganese, or Iron
mineral
Chert (with Epidote/Quartz veining)
Cryptocrystalline silica (SiO2) with Epidote/Quartz inclusions
sedimentary
Chert (Yellow Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Nodule)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (Arrowhead Shard)
Microcrystalline silica (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz or Cryptocrystalline Silica (SiO2)
sedimentary
Pearl
Organic gemstone (Calcium carbonate / CaCO3 + Conchiolin)
mineral
Fossiliferous Limestone
Calcite (CaCO3) with Bioclastic inclusions
sedimentary
Black Jasper (Black Onyx substitute)
Silicon Dioxide (SiO2) with carbonaceous impurities
sedimentary (microcrystalline quartz)
River Cobble (Sandstone)
Arenite (primarily SiO2)
sedimentary
White Coral
Corallium rubrum (biocarbonate calcium) / CaCO3
mineral
Pink Opal
Hydrated Silica (SiO2·nH2O)
mineral
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
fossil
Chert (Jasper/Chalcedony variant)
Microcrystalline Quartz (SiO2)
sedimentary
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
sedimentary
Petrified Wood (Silicified Wood)
Silicified fossil wood (SiO2)
metamorphic
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Chert (White-Grey variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert (specifically Flint or Common Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (with Lichen)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (and Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (White Chert)
Silicon Dioxide (SiO2)
sedimentary
Amber
Succinite (fossilized tree resin)
mineraloid / sedimentary organic material
Amber
Succinite (specifically for Baltic amber); chemical formula approximately C10H16O
Mineraloid
Amber
Succinite (a variety of fossilized tree resin); chemical formula appx. C10H16O
mineraloid
Agatized Petrified Wood
Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood
metamorphic
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
mineral
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper-like Silicate)
Microcrystalline quartz (SiO2)
sedimentary
Jasper
Silicon Dioxide (SiO2)
mineral
Fossil Shark Tooth (Sand Tiger Shark type)
Carcharias sp. (likely Odontaspis)
fossil
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)
mineral
Flower Jasper
Agatized Fossil Coral / Chalcedony (SiO2)
sedimentary