Fossil Coral (Petoskey Stone / Rugose Coral)
Hexagonaria percarinata (or similar fossilized rugose/tabulate coral)
fossil
Category
Mineral (Biogenic Replacement)
Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4 in Vesicular Basalt
igneous
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
sedimentary
Fossilized cylindrical shell or bone fragment
Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone
fossil
Petrified Wood
Silicified wood (Quartz / Chalcedony replacement of organic cellulose)
fossil
Dinosaur Bone (Gembone)
Petrified Dinosaur Bone (Apatite/Silica replacement)
sedimentary
Chert (Jasper variety) with Iron Oxide staining
Cryptocrystalline Quartz (SiO2) with Goethite/Limonite impurities
sedimentary
Chert (Flint variety)
Chert (SiO2)
sedimentary
Chert (containing Flint and Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Mookaite Jasper
Silicified Radiolarite (SiO2)
sedimentary
Crinoid Stem Fossil
Crinoidea (Class) / Calcite (CaCO3)
fossil
Chert (Flint variety)
Silicon Dioxide (SiO2)
sedimentary
Chert (variations include Chalcedony and Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2 - Quartz/Chalcedony replacement)
Mineral / Fossil
Red Jasper
Silicon dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
sedimentary
Chert (specifically a stream-worn Chert Nodule)
Sedimentary Cryptocrystalline Quartz (SiO2)
sedimentary
Brecciated jasper (likely red-and-cream jasper)
Jasper, an opaque microcrystalline variety of quartz; primarily cryptocrystalline SiO₂ with iron-oxide staining and possible chalcedony/quartz veining
gemstone
Petrified Wood
Silicon Dioxide Fossilized Wood (SiO2)
fossil
Galena
Galena (Lead Sulfide), PbS
mineral
Chert (Jasper/Common Opal transition)
Microcrystalline Quartz (SiO2) with iron oxide inclusions
sedimentary
Petrified Wood
Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)
Mineral/Fossil (Sedimentary context)
Chert (Jasper variation)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement) SiO2
sedimentary
Petrified Wood
Silicified wood (Quartz replacement of organic wood structure)
fossil
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Chert (Flint Nodule)
Microcrystalline and Cryptocrystalline Quartz (SiO2)
sedimentary
Chalcedony (Agate/Seashell replacement)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
mineral
Red Jasper with Fossils
Silicified Fossiliferous Jasper (Chert variant, SiO2)
sedimentary
Fossil Coral
Hexagonaria or Rugose Coral (petoskey stone / fossilized rugose or tabulate coral)
fossil
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
fossil
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Fossil Coral (Petoskey Stone / Hexagonaria)
Hexagonaria percarinata (Silicified/Calcite Replacement Coral)
fossil
Fossilized Horn Coral
Rugosa (Tetracoralla)
fossil
White Jade (Nephrite)
Nephrite, Ca2(Mg,Fe)5Si8O22(OH)2
Mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of organic matter)
sedimentary
Fossil-bearing sedimentary rock, possibly fossil wood or bone
Indeterminate silicified/carbonate fossil in sandstone or mudstone
fossil
Petrified Wood
Silicified wood (primarily Silicon Dioxide - SiO2)
mineral (silicate-replaced organic material)
Petoskey Stone (Petrified Favosites)
Favosites (extinct colonial coral), CaCO3 with Silica replacement
sedimentary
Synthetic Ruby (Jewel Bearings)
Synthetic Corundum (Al2O3 doped with Chromium)
mineral
Yellow Chalcedony
Chalcedony (a cryptocrystalline variety of Quartz, SiO₂)
Mineral