Petrified Wood
Silicified Wood (SiO2)
sedimentary
Category
Organic Crystal (Mineraloid)
Browse organic crystal (mineraloid) specimens identified by the Rock Identifier community.
Chert (Chalcedony/Agate)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Banded Agate (specifically Moss Agate or Plume Agate variety)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
mineral
Ferruginous Sandstone (Ironstone)
Arenite with Iron-Oxide Cement (FeO(OH)·nH2O / Fe2O3)
sedimentary
Carved Mottled Greenish-Yellow Crystal/Glass Object
Unknown; possibly a form of quartz (chalcedony/jadeite/nephrite) or glass/resin.
Man-made Object/Uncertain Mineral
Opalite
Synthetically produced glass (Silicon Dioxide with metallic inclusions)
Mineraloid (Man-made Glass)
Petrified Wood
Silicified wood / Xylopal
fossil
Jasper
Jasper (Silica-rich microcrystalline Quartz, SiO2 with Fe2O3 impurities)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
Mineral (Variety of Chalcedony)
Petrified Wood
Silicified wood (Quartz replacement)
fossil
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Chert (variations include Flint/Jasper)
Cryptocrystalline Silicon Dioxide (SiO2)
sedimentary
Basaltic Tuff / Volcanic Breccia
Pyroclastic Breccia / Lithic Tuff
igneous
Chert (often colloquially referred to as Flint)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Wood Beads (Palmwood/Ebony)
Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.
Organic Gem Material (Botanical)
Jasper
Silicon Dioxide (Microcrystalline Quartz / Chalcedony)
sedimentary
Green Banded Chert (Agate/Jasper)
Silicon Dioxide (SiO2) with trace impurities of Chlorite or Glauconite
sedimentary
Sulfidic Mudstone with Pyrite/Goethite
Sulfidic Siltstone/Mudstone (FeS2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Banded Chert (or River Jasper)
Microcrystalline Quartz (SiO2) with iron oxide impurities
sedimentary
Petrified Wood
Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)
Mineral/Fossil (Sedimentary context)
Moss Agate
Silicon Dioxide (SiO2) with inclusions
mineral
Chert (specifically Blue Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Green Calcite
Calcium Carbonate (CaCO3)
mineral
Synthetic Resin / Plastic Figurine
Synthetic Polymer (Copolymer of Polyethylene or Resin)
Mineraloid-like Synthetic Material
Sandstone with Trace Fossils
Quartz Arenite with Bioturbation (Trace Fossils)
sedimentary
Opalite
Synthetic Opalised Glass
Mineral (Synthetic / Man-made)
Agate (Geode/Nodule)
Chalcedony (cryptocrystalline silica, SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
mineral
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Jasper
Agate/Jasper (Microcrystalline Quartz, SiO2)
sedimentary
Septarian Nodule (Dragon Stone)
Septarian Concretion (CaCO3 with Siderite and Calcite)
sedimentary
Chert (Yellow Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Travertine (often colloquially called Tufa)
Chemical Sedimentary Calcium Carbonate (CaCO3)
sedimentary