Chalcedony
Cryptocrystalline Quartz (SiO2)
mineral
Category
Mineral (Organic)
Browse mineral (organic) specimens identified by the Rock Identifier community.
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Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
sedimentary
Chert with Iron Oxide Staining
Microcrystalline Quartz (SiO2) with Limonite/Goethite staining
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (containing Calcite or Quartz inclusions)
Silicon Dioxide (SiO2) with varying mineral impurities
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide
mineral
Tahitian Pearl
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
mineral
Moss Agate
Silicon Dioxide with inclusions (SiO2 + impurities)
mineral
Coal (Anthracite / Bituminous)
Organic Sedimentary Rock (Carbon-based)
sedimentary
Horse Chestnut (Buckeye seed)
Aesculus hippocastanum seed
Organic (Non-geological)
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide/Quartz)
metamorphic
Pearl
Calcium carbonate (CaCO3) + organic conchiolin (Biogenic Mineral)
mineral
Chert / Chalcedony
Silicon Dioxide (SiO2)
sedimentary
Vivianite
Vivianite, Fe2+3(PO4)2·8H2O
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Pyrite in Shale
Iron Disulfide (FeS2) in Sedimentary Shale
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Agatized Petrified Wood
Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood
metamorphic
Red Jasper with Quartz
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood Agate
Silicified Wood (primarily SiO2)
fossil
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
mineral
Moss Agate
Cryptocrystalline Quartz (SiO2 with Manganese or Iron Oxide inclusions)
mineral
Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin, CaCO3
gemstone
Pyrite
Iron Sulfide (FeS2)
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Concretionary Sandstone
Clastic Sedimentary Rock (Sandstone with secondary mineral cementation)
sedimentary
Pearl (Biogenic Mineral)
Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3
mineral
Turquoise and Red Coral
Turquoise: CuAl6(PO4)4(OH)8·4H2O; Red Coral: Corallium rubrum (organic gemstone)
mineral
Chert
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Calligraphy Stone
Mariam Jasper (Fossiliferous Limestone with Hematite and Iron)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Fossil Coral
Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)
fossil
Moss Agate
Silicon Dioxide (SiO2) with inclusions
mineral
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
Mineral
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Concrete or asphalt-like aggregate surface with a dark fragment
Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock
sedimentary
Ironstone Concretion
Ironstone (Limonite/Goethite Concretion)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Zebra Rock / Zebra Marble
Banded Limestone-Marble Transition
metamorphic