Ironstone Concretion / Limonite Node
Goethite and Limonite (FeO(OH) nH2O)
sedimentary
Category
Industrial Byproduct (Often Mistaken For Obsidian Or Mineral)
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
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Sodalite
Sodalite, Na8(Al6Si6O24)Cl2
mineral
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
mineral
Chert Concretion (with typical hematite/limonite staining)
Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)
sedimentary
Obsidian
Obsidian (principally SiO2/Silicon dioxide)
igneous
Tumbled black stone, likely obsidian
Obsidian — volcanic glass, chiefly silica-rich rhyolitic composition
igneous
Tumbled dark-green serpentine
Serpentinite; chiefly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile (Mg₃Si₂O₅(OH)₄)
metamorphic
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
igneous
Amber (polished piece)
Fossilized tree resin; amber is an organic mineraloid, not a true mineral
gemstone
Snowflake Obsidian
Hydrated Volcanic Glass with Cristobalite inclusions
igneous
Black Obsidian
Volcanic Glass (felsic)
igneous
Mica Schist with Quartz
Schist containing Muscovite and Quartz
metamorphic
Polished black-and-white tourmaline
Schorl tourmaline, complex borosilicate; commonly black schorl with quartz or feldspar inclusions
mineral
Geode (unopened)
Quartz-filled Geode (SiO2)
sedimentary
Obsidian
Volcanic Glass (SiO2 rich)
igneous
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
igneous
Sandstone Concretion
Clastic sedimentary rock (primarily Quartz SiO2)
sedimentary
Scoria (Lava Rock)
Mafic extrusive volcanic rock (Scientific formula varies based on mineral content: primarily SiO2, MgO, and FeO)
igneous
Ironstone Concretion
Ironstone (Limonite/Goethite Concretion)
sedimentary
Obsidian (black volcanic glass)
Obsidian; primarily amorphous SiO₂-rich rhyolitic glass
igneous
Tumbled black stone, likely basalt or black jasper
Likely fine-grained basalt (plagioclase–pyroxene); exact identification requires testing
igneous
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
mineral
Obsidian (likely black obsidian)
Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)
igneous
Obsidian (likely black obsidian)
Volcanic glass; primarily SiO₂-rich rhyolitic composition
igneous
Syenite
Syenite (Phaneritic Igneous Rock)
igneous
Sandstone Cobble with Liesegang Rings
Arenite with iron oxide precipitation (SiO2 matrix with Fe2O3 banding)
sedimentary
Ferruginous Sandstone Concretion (Ironstone Phosphorite)
Ferruginous Sandstone (variable Fe-oxide/hydroxide composition)
sedimentary
Ferruginous Quartzite
Quartzite with Hematite/Limonite inclusions (SiO2)
metamorphic
Apache Tear
Hydrated Obsidian (Volcanic Glass)
Igneous
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Black obsidian
Volcanic glass, predominantly rhyolitic silica glass (approximately 70–80% SiO₂)
igneous
Blue Apatite
Calcium Phosphate (Ca5(PO4)3(F,Cl,OH))
mineral
Iron-stained Quartz
Silicon Dioxide (SiO2) with Limonite/Hematite inclusions
mineral
Blue Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Quartz with Iron Staining
Silicon Dioxide (SiO2) with Limonite/Hematite inclusions
mineral
Orange Quartz
Crystalline Silicon Dioxide (SiO2) with iron oxide inclusions
mineral
Aventurine
Aventurine Quartz (SiO2 with inclusions of Fuchsite)
metamorphic
Likely rough pyrite specimen
Pyrite (FeS₂)
mineral
Weathered garnet-bearing gneiss
Quartz–feldspar–mica gneiss with almandine garnet, chiefly Fe₃Al₂(SiO₄)₃
metamorphic
Ironstone Concretion (Limonite/Goethite)
Ironstone (composed primarily of Goethite FeO(OH) and Limonite)
sedimentary
Scoria (Vesicular Basalt)
Scoria (Extrusive Igneous Rock)
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral