Obsidian
Amorphous volcanic glass (SiO2)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian
Amorphous volcanic glass (SiO2)
Obsidian
Volcanic Glass (SiO2)
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
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)
Goldstone
Aventurine Glass (SiO2 + Cu small inclusions)
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Obsidian
Obsidian (Volcanic Glass)
Goldstone (Brown)
Aventurine glass
Obsidian
Volcanic Glass (SiO2)
Obsidian
Volcanic Glass (70-75% SiO2)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Obsidian
Volcanic Glass (SiO2)
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
Ironstone Concretion
Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)
Ironstone Nodule
Ironstone (Ferruginous Rock)
Obsidian
Volcanic Glass (Amorphous SiO2)
Limestone Concretion (Botryoidal/Calcareous Nodules)
Calcium Carbonate Concretion (CaCO3)
Sandstone concretion
Arenite sedimentary rock (concretion/nodule)
Strawberry Quartz (Aventurine)
Silicon Dioxide with Hematite/Lepidocrocite inclusions (SiO2)
Dendritic Agate (River Pebble)
Silicon Dioxide (SiO2) with Manganese or Iron oxide inclusions
Green Aventurine
Aventurine Quartz (SiO2 with Fuchsite inclusions)
Apache Tear
Obsidian (Hydrated Volcanic Glass - SiO2)
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Obsidian
Volcanic Glass (70-75% SiO2)
Ironstone Concretion
Goethite-rich Siltstone / Siderite (FeCO3)
Pink and Green Tourmaline (Tumbled)
Elbaite (Na(Li,Al)3Al6(BO3)3Si6O18(OH)4)
Tumbled black stone, likely black obsidian
Obsidian — natural volcanic glass, primarily SiO₂
Obsidian
Volcanic Glass (SiO2 + impurities)
Obsidian
Volcanic glass
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
Red Quartz (Ferruginous Quartz)
Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)
Obsidian
Volcanic Glass
Obsidian
Volcanic Glass (Amorphous Silica)
Obsidian
Volcanic glass (high silica volcanic rock)
Obsidian
Volcanic Glass (70-75% SiO2 with MgO and Fe3O4)
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
Dendritic Jasper (River Stone)
Silicon Dioxide (SiO2) with Manganese/Iron Oxide inclusions
Obsidian
Obsidian (principally SiO2 silicon dioxide)
Sandstone Concretion
Sandstone (Sedimentary Rock) with silica or calcite cement
Dendritic Siltstone
Siltstone with Manganese Dendrites (MnO2)