Limonite
Hydrous Iron Oxide (often Goethite FeO(OH), Lepidocrocite γ-FeO(OH), and other amorphous iron oxyhydroxides)
Category
Browse organic (non geological) specimens identified by the Rock Identifier community.
Limonite
Hydrous Iron Oxide (often Goethite FeO(OH), Lepidocrocite γ-FeO(OH), and other amorphous iron oxyhydroxides)
Snowflake Obsidian
Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)
Obsidian
Volcanic Glass (SiO2 + impurities)
Petrified Wood
Silicified Wood (primarily SiO2)
Quartz (Iron-stained)
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Conglomerate
Conglomerate (Sedimentary Clastic Rock)
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite/Magnetite inclusions)
Liesegang Ring Siltstone
Siltstone with iron oxide Liesegang bands
Pearls
Pearl: biomineralized aragonite (CaCO₃) and conchiolin
Obsidian
Obsidian (Volcanic Glass)
Green Chert
Silicon Dioxide (SiO2)
Petrified Wood
Petrified Wood (Silicified Wood)
Biological Bone (Patella/Knee)
Patella (part of the Human Skeletal System)
Mixed Quartz and Jasper Pebbles
Silicon Dioxide (SiO2)
Travertine (Tufa)
Chemical Limestone (CaCO3)
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Obsidian (in jewelry setting)
Volcanic Glass (Amorphous Silica)
Goldstone (Red/Brown)
Aventurine Glass (SiO2 with Copper inclusions)
Moss Agate
Silicon Dioxide with inclusions (SiO2)
Petrified Wood
Silicified Wood (SiO2 permineralization)
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Banded sandstone pebble
Quartz-rich lithic sandstone; exact provenance and composition require testing
Quartz Geode
Silicon Dioxide (SiO2)
Graphite
Graphite (Native Carbon, C)
Chert (Cherty Flint/Jasper variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Chert (Nodule)
Silicon Dioxide (SiO2)
Obsidian
Obsidian (principally SiO2/Silicon dioxide)
Black Obsidian
Obsidian (Volcanic Glass)
Small seashell fossil or shell fragment
Likely calcium-carbonate shell material, chiefly aragonite or calcite; exact species indeterminate
Note: Item is a Synthetic/Man-made Object
Titanium-coated Stainless Steel (Fe-Cr-Ni-Ti)
Fossilized Shark Tooth
Chondrichthyes tooth
Red Jasper
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Chert (Brown variety / Common Jasper)
Microcrystalline Quartz (SiO2)
Chert (often called Flint or Jasper locally)
Chert (Microcrystalline Quartz, Formula: SiO2)
Fossiliferous Shale Matrix
Clastic Sedimentary Rock with Brachiopod or Mollusk shell fragments
Quartzite
Quartzite (primarily SiO2)
Anthracite Coal
Anthracite (Carbon-based organic sedimentary rock exposed to metamorphic heat/pressure; Chemical composition is approximately 86%–98% Carbon)
Amber
Succinite (C10H16O)
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)
Obsidian
Obsidian (Volcanic Glass)