Fossil Coral
Hexagonaria (or Rugose/Tabulate coral fossilized in calcium carbonate)
fossil
Category
Sedimentary (Fossilized Organic Remain)
Browse sedimentary (fossilized organic remain) specimens identified by the Rock Identifier community.
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Dendritic Opal
Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Orange cabochon gemstone, likely amber or amber-like resin
Natural amber: fossilized plant resin (organic mineraloid), commonly succinite; exact identification requires testing
gemstone
White limestone or chalky carbonate rock
Calcite-rich limestone; possibly chalk (CaCO₃)
sedimentary
Chert Concretion
Microcrystalline Quartz (SiO2) in Carbonate Matrix
sedimentary
Ferruginous Sandstone with Concretion
Sandstone (SiO2 dominated with Fe2O3 cement)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert or Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Iron-stained)
Silicon Dioxide (SiO2)
sedimentary
Banded Chert
Silicon Dioxide (SiO2)
sedimentary
Porphyry (specifically Porphyritic Basalt or Andesite)
Porphyritic extrusive igneous rock (Mg,Fe)2SiO4 (Olivine inclusions/Plagioclase Feldspar)
igneous
Fossilized Shark Tooth (Otodus obliquus)
Otodus obliquus (Mineral composition: Bio-apatite/Calcium Phosphate replaced by various minerals)
sedimentary (fossil)
Fossilized Rugose Coral (Horn Coral)
Order Rugosa (extinct tetra-coral)
sedimentary
Fossilized Rugose Coral (Horn Coral)
Rugosa (Order) - often Grewingkia or Zaphrenthis
sedimentary
Sandstone with Brachiopod Mold Fossil
Sedimentary rock (Sandstone) with indeterminate Brachiopod mold
fossil
Chert (Red Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Fossilized Coral (Petoskey Stone type)
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Fossilized Coral (Petoskey Stone type)
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Glauconite (Greensand)
Glauconite (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2
sedimentary
Coral Fossil / Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
fossil
Fluorite
Calcium Fluoride (CaF2)
mineral
Fossiliferous Limestone
Calcite (CaCO3) matrix with biogenic fragments
sedimentary
Limestone (River Pebble)
Calcium Carbonate (CaCO3)
sedimentary
Bituminous Coal
Organic Sedimentary Rock (Carbon-based)
sedimentary
Jasper
Silicon dioxide (Quartz variety), SiO2
sedimentary
Chert (or Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Pyrite
Iron Disulfide (FeS2)
mineral
Chert (Chalcedony/Common Opal)
Microcrystalline Quartz (SiO2)
sedimentary
Pyrite (Fool's Gold) Cube
Iron Sulfide (FeS2)
mineral
Flint (Chert)
Silicon Dioxide (SiO2)
sedimentary
Chalcedony (Common Opal variant)
Silicon dioxide (SiO2) with varying levels of hydration
mineral
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz / Chalcedony: SiO2)
sedimentary
Chert (Flint)
Chert (Microcrystalline or cryptocrystalline Quartz - SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary