Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Obsidian
Obsidian (Volcanic Glass, SiO2)
Apache Tears (Obsidian)
Hydrated Volcanic Glass (Amorphous SiO2 + H2O)
Pyrite with Iron Oxides (Fool's Gold in Matrix)
Iron Sulfide (FeS2)
Green Chalcedony (likely Chrysoprase or Green Onyx)
Silicon Dioxide (SiO2) with trace nickel or chromium inclusions
Fuchsite
Chromium-rich Muscovite (KAl2(AlSi3O10)(OH,F)2 with Cr replacements)
Obsidian
Obsidian (principally SiO2 silicon dioxide)
Chalcopyrite
Copper Iron Sulfide (CuFeS2)
Sodalite
Sodalite [Na8(Al6Si6O24)Cl2]
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
Sodalite
Sodalite, Na8(Al6Si6O24)Cl2
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
Ironstone Concretion
Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)
Obsidian
Obsidian (Volcanic glass), SiO2 (major component)
Obsidian
Volcanic Glass (SiO2 rich)
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Volcanic Glass (Amorphous Silica)
Obsidian
Volcanic glass (Mainly SiO2)
Ironstone Concretion (Limonite/Goethite)
Goethite/Limonite concretion (FeO(OH)·nH2O)
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with inclusions of Hematite or Magnetite)
Pumice
Vesicular Rhyolite or Dacite
Obsidian
Volcanic Glass (SiO2)
Red Quartz (Ferruginous Quartz)
Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)
Dumortierite Quartz
Dumortierite (Al7BCuO15)
Ironstone Concretion
Goethite-rich Siltstone / Siderite (FeCO3)
Quartz Pebble
Silicon Dioxide (SiO2)
Sandstone Concretion
Sedimentary Clastic Rock (Silicate-rich)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Obsidian
Obsidian (Volcanic glass, primarily SiO2)
Dendritic Siltstone
Siltstone with Manganese Dendrites (MnO2)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
Yellow Calcite
Calcium Carbonate (CaCO3)
Concretion
Septarian Concretion (Fragmentary)
Sandstone Concretion
Sandstone (Sedimentary Rock) with silica or calcite cement
Ironstone Concretion
Siderite or Hematite Concretion (FeCO3 or Fe2O3)
Obsidian
Volcanic glass
Pyrite
Iron Sulfide (FeS2)
Sandstone Concretion
Clastic Sedimentary Concretion (SiO2 with Iron Oxide)
Obsidian
Volcanic Glass (Silicon Dioxide with impurities)
Sandstone (likely River-tumbled Picture Sandstone)
Arenite (predominantly SiO2 with iron oxide impurities)
Goldstone (Brown)
Aventurine glass