Chalcedony
Cryptocrystalline Quartz (SiO2)
Category
Browse organic mineral specimens identified by the Rock Identifier community.
Chalcedony
Cryptocrystalline Quartz (SiO2)
Picture Jasper
SiO2
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
Chert with Iron Oxide Staining
Microcrystalline Quartz (SiO2) with Limonite/Goethite staining
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide/Quartz)
Moss Agate
Silicon Dioxide with inclusions (SiO2 + impurities)
Chert (containing Calcite or Quartz inclusions)
Silicon Dioxide (SiO2) with varying mineral impurities
Vivianite
Vivianite, Fe2+3(PO4)2·8H2O
Petrified Wood
Silicified Wood (SiO2)
Pyrite in Shale
Iron Disulfide (FeS2) in Sedimentary Shale
Petrified Wood
Silicified Wood (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin, CaCO3
Agatized Petrified Wood
Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
Moss Agate
Cryptocrystalline Quartz (SiO2 with Manganese or Iron Oxide inclusions)
Chert / Chalcedony
Silicon Dioxide (SiO2)
Red Jasper with Quartz
Microcrystalline Quartz (SiO2)
Petrified Wood Agate
Silicified Wood (primarily SiO2)
Calligraphy Stone
Mariam Jasper (Fossiliferous Limestone with Hematite and Iron)
Moss Agate
Silicon Dioxide (SiO2) with inclusions
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
Horse Chestnut (Buckeye seed)
Aesculus hippocastanum seed
Concretionary Sandstone
Clastic Sedimentary Rock (Sandstone with secondary mineral cementation)
Turquoise and Red Coral
Turquoise: CuAl6(PO4)4(OH)8·4H2O; Red Coral: Corallium rubrum (organic gemstone)
Petrified Wood
Silicified Wood (SiO2)
Pyrite
Iron Sulfide (FeS2)
Ironstone Concretion
Ironstone (Limonite/Goethite Concretion)
Petrified Wood
Silicified Wood (SiO2)
Chert
Chert (Microcrystalline Quartz, SiO2)
Coal (Anthracite / Bituminous)
Organic Sedimentary Rock (Carbon-based)
Zebra Rock / Zebra Marble
Banded Limestone-Marble Transition
Petrified Wood
Silicified Wood (SiO2)
Petrified Wood
Silicified Wood (primarily SiO2)
Fossil Coral
Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)
Pearl
Calcium carbonate (CaCO3) + organic conchiolin (Biogenic Mineral)
Petrified Wood
Silicified Wood (SiO2)
Coprolite
Fossilized Feces
Sandstone
Arenicola (comprising mostly Quartz, SiO2)
Petrified Wood
Silicified Wood (SiO2)
Fossil bivalve shell
Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features
Dyed Agate (Tumbled)
Silicon Dioxide (Chalcedony variety, artificially dyed)