Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Obsidian (Amorphous volcanic glass, predominantly SiO2)
Obsidian
Obsidian (Volcanic Glass) SiO2 (70% or more)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Sandstone (Micaceous Sandstone)
Arenite (SiO2 with KAl2(AlSi3O10)(OH)2 inclusions)
Ferruginous Siltstone or Mudstone
Ferruginous Siltstone / Goethitic Sandstone
Pumice
Vesicular Rhyolite or Dacite
Ironstone Concretion
Siderite or Limonite Concretion
Ironstone Concretion (Siderite Nodules)
Siderite (FeCO3) in Mudstone or Sandstone matrix
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
Sandstone (likely River-tumbled Picture Sandstone)
Arenite (predominantly SiO2 with iron oxide impurities)
Green Aventurine
Silicon Dioxide (SiO2) with inclusions of Fuchsite (mica)
Obsidian
Obsidian (Amorphous volcanic glass)
Green Aventurine
Aventurine Quartz (SiO2 with inclusions of Fuchsite mica)
Concretion
Septarian concretion (likely containing Calcite or Siderite)
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Dumortierite Quartz
Al7(BO3)(SiO4)3O3
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Limonite Concretion
Limonite (Hydrated Iron Oxide) FeO(OH)·nH2O
Obsidian
Volcanic Glass (SiO2)
Obsidian
Amorphous volcanic glass (SiO2)
Dendritic Jasper (River Stone)
Silicon Dioxide (SiO2) with Manganese/Iron Oxide inclusions
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Amorphous volcanic glass (primarily SiO2)
Obsidian
Obsidian (volcanic glass), predominantly Silicon Dioxide (SiO2)
Black Tourmaline
Schorl (Na(Fe2+)_{3}Al_{6} (BO_{3})_{3} (Si_{6}O_{18})(OH)_{4})
Dendritic Agate (River Pebble)
Silicon Dioxide (SiO2) with Manganese or Iron oxide inclusions
Blue Apatite
Fluorapatite / Chlorapatite [Ca5(PO4)3(F,Cl,OH)]
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
Obsidian
Volcanic Glass (70-75% SiO2)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Quartz Pebble
Silicon Dioxide (SiO2)
Obsidian
Volcanic Glass (70-75% SiO2)