Quartzite
Quartzite (primarily SiO2)
metamorphic
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
Dalmatian Jasper
Peralkaline rhyolite with Arfvedsonite inclusions
igneous
Limonite Concretion
Limonite (Hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
sedimentary
Sandstone Concretion
Sedimentary concretion
Sedimentary
Obsidian
Obsidian (volcanic glass)
igneous
Serpentine
Antigorite/Lizardite/Chrysotile group, Mg3Si2O5(OH)4
metamorphic
Green Aventurine
SiO2 (Silicon Dioxide) with Fuchsite inclusions
mineral
Concretion in Shale
Siltstone/Shale with Siderite or Calcareous concretions
sedimentary
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Green Glass Cullet / Recycled Glass
Amorphous Silicon Dioxide (SiO2) with various metal oxides
Man-made Glass (Not a natural rock or mineral)
Obsidian (Gold Sheen)
Obsidian (SiO2 + impurities)
igneous
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
igneous
Apache Tear (Obsidian)
Obsidian
Igneous
Black Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Obsidian (principally SiO2)
igneous
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Siderite Concretion
Ironstone (Siderite) Concretion, FeCO3
sedimentary
Obsidian (likely black volcanic glass)
Obsidian; silica-rich, noncrystalline volcanic glass, typically rhyolitic (approximately 70–75% SiO₂)
igneous
Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Ironstone Nodules (Iron Concretion)
Siderite or Hematite Concretion
sedimentary
Polished black stone, likely black obsidian
Obsidian (volcanic glass; mainly SiO₂)
igneous
Dumortierite Quartz
Dumortierite in Quartz (Al6O3(BO3)(SiO4)3)
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
igneous
Ironstone Concretion
Ferruginous Siltstone/Ironstone (Fe2O3)
sedimentary
Sandstone Concretion
Sandstone (Sedimentary rock, mostly SiO2)
sedimentary
Black Obsidian
Volcanic Glass (SiO2)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartz Pebble (with Manganese dendrites/staining)
Silicon Dioxide (SiO2) with Manganese Oxide impurities
mineral
Dumortierite Quartz (Blue Quartz)
Al7BO3(SiO4)3O3 with Quartz (SiO2)
mineral
Manganese Dendrite on Siltstone
Manganese Oxide (pyrolusite or psilomelane) Dendrites
mineral/sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)
igneous
Siltstone with iron staining
Siltstone (primarily SiO2 with FeO(OH) coatings)
sedimentary
Amazonite
KAlSi3O8 (Potassium Aluminum Silicate) - a variety of Microcline Feldspar
mineral
Dendritic sandstone
Sandstone with Manganese Oxide dendrites
sedimentary
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Jasper (Multi-colored) / Sea Glass Slag
Silicon Dioxide (SiO2) with impurities of Iron Oxide
Sedimentary (if natural Jasper) or Artificial (if Slag)
Dumetierite in Quartz (Blue Quartz)
Dumortierite (Al7BO3(SiO4)3O3) inclusions in Quartz (SiO2)
metamorphic