Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
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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Obsidian
Obsidian (Volcanic Glass)
igneous
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (70–75% SiO2)
Igneous
Manganese Oxide Crust on Limestone
Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3
sedimentary
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide)
Igneous
Sandstone with Manganese Dendrites
Arenite (mostly SiO2) with Manganese Oxide inclusions (MnO2)
sedimentary
Mica-rich Sandstone or Micaceous Schist Weathering
Micaceous Schist (Muscovite-Quartz composition)
Metamorphic or Sedimentary depending on local grade
Ironstone Concretion / Hematite Nodules
Ferruginous Sedimentary Rock (primarily Hematite Fe2O3 and Goethite FeO(OH))
sedimentary
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Mica Schist with Pyrite
Muscovite/Biotite Schist with Iron Sulfide (FeS2)
metamorphic
Obsidian
Obsidian (volcanic glass)
igneous
Obsidian
Volcanic glass
igneous
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
igneous
Bismuth
Bismuth (element Bi) with oxidized thin-film interference layer
mineral
Carborundum (Silicon Carbide)
Silicon Carbide (SiC)
mineral (synthetic)
Green Glass Cullet / Recycled Glass
Amorphous Silicon Dioxide (SiO2) with various metal oxides
Man-made Glass (Not a natural rock or mineral)
Obsidian
Obsidian (Amorphous volcanic glass)
igneous
Mother of Pearl (Nacre)
Aragonite (CaCO3) with Organic Matrix
mineral
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Silver (Native Element)
Ag (Argentum)
mineral
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Tiger's Eye, Hematite, and Black Obsidian Bracelet
SiO2 (Tiger's Eye), Fe2O3 (Hematite), and 70-75% SiO2 (Obsidian)
mineral
Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Aura Quartz (Pink/Rose Aura Quartz)
Silicon Dioxide (SiO2) bonded with Platinum and/or Silver
mineral
Dalmatian Jasper
Peralkaline rhyolite with Arfvedsonite inclusions
igneous
Green Quartz (Prasiolite or Aventurine)
Silicon Dioxide (SiO2)
mineral
Limonite Concretion
Limonite (Hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
sedimentary
Dendritic Siltstone
Siltstone with Manganese Oxide dendrites (MnO2)
sedimentary
Obsidian
Obsidian (principally SiO2)
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Sandstone Concretion
Sedimentary concretion
Sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Black Obsidian
Volcanic Glass (SiO2)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Snowflake Obsidian
Obsidian with Cristobalite inclusions
igneous