Obsidian
Amorphous volcanic glass (primarily SiO2)
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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Tumbled mahogany obsidian
Volcanic glass; primarily SiO₂ with iron-oxide-rich brown inclusions
igneous
Mahogany Obsidian
Volcanic Glass with Hematite inclusions
igneous
Sulfur
Native Sulfur (S)
mineral
Sulfur (with possible Cullet Glass or Slag imitation)
Native Sulfur (S8)
mineral
Manganese-coated Sandstone
Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)
sedimentary
Yellow Aventurine
Quartzite with inclusions (SiO2)
metamorphic
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
metamorphic
Polished red jasper or mahogany obsidian (likely jasper)
Microcrystalline quartz, SiO₂, with iron-oxide inclusions
mineral
Obsidian
Volcanic Glass
igneous
Sheen Obsidian
Volcanic glass (SiO2 with inclusions)
igneous
Sandstone (Ferruginous Concretion)
Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement
sedimentary
Mahogany Obsidian
Volcanic Glass with Hematite or Magnetite (SiO2 + Fe2O3)
igneous
Silver (Jewelry form)
Native Silver (Ag)
mineral
Ironstone concretion
Siderite or Limonite concretion (FeCO3 or FeO(OH)·nH2O)
sedimentary
Bituminous Coal
Coal (Organically derived sedimentary rock)
sedimentary
Obsidian
Volcanic Glass (Mainly SiO2)
igneous
Tiffany Stone
Bertrandite-Bearing Fluorite Hyalite Opal
metamorphic
Unidentified Dark Mineral or Rock
Indeterminate (Likely Silicon Dioxide or Carbon-based)
mineral
Siltstone/Sandstone (possibly Wonderstone or Picture Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide inclusions)
Sedimentary
Ironstone Concretion
Siderite or Hematite-rich Concretion (FeCO3 / Fe2O3)
sedimentary
Obsidian
Obsidian (Volcanic Glass)
igneous
Chert Concretion (Flint)
Silicon Dioxide (SiO2)
sedimentary
Obsidian
Volcanic glass (high silica SiO2)
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions
igneous
Sandstone Concretion
Ferruginous Sandstone Concretion
sedimentary
Black tourmaline (likely schorl)
Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Black Obsidian
Amorphous volcanic glass (SiO2)
igneous
Ironstone Nodules (Limonite/Hematite)
Goethite/Hematite mix (FeO(OH)/Fe2O3)
sedimentary
Blue Apatite
Fluorapatite / Ca5(PO4)3F
mineral
Sandstone Concretion
Sedimentary Concretion (SiO2 or CaCO3 cemented)
sedimentary
Sandstone with Dendritic Inclusions
Quartzose Sandstone
sedimentary
Obsidian
Volcanic Glass (SiO2)
igneous
Dendritic Agate (Tumbled)
Silicon Dioxide (SiO2) with inclusions
mineral
Mudstone/Siltstone with Liesegang Bands
Argillaceous Sedimentary Rock with Chemical Banding
sedimentary
Obsidian
Obsidian (Volcanic Glass)
igneous
Black Obsidian
Obsidian, SiO2 (amorphous)
Igneous rock (Volcanic glass)
Black Onyx
Silicon Dioxide (SiO2)
mineral
Green Aventurine
Quartz with Fuchsite inclusions (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)
mineral
Black Obsidian
Volcanic Glass (Silicon Dioxide with impurities)
igneous