Obsidian
Volcanic Glass (SiO2 rich)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian
Volcanic Glass (SiO2 rich)
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
Concretion
Sedimentary Concretion (Ironstone / Calcite Concretion)
Ironstone Concretion
Siderite or Hematite Concretion (FeCO3 or Fe2O3)
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Obsidian (Volcanic glass), SiO2 (major component)
Obsidian
Volcanic glass (Mainly SiO2)
Obsidian
Volcanic Glass (Amorphous Silica)
Pyrite
Iron Sulfide (FeS2)
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Quartz Pebble
Silicon Dioxide (SiO2)
Sandstone
Arenite (SiO2 based)
Obsidian
Volcanic glass (SiO2)
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)
Ironstone Concretion
Siderite or Limonite Concretion
Quartzite with Hematite staining
Quartzite (SiO2)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Obsidian
Obsidian (Volcanic Glass, SiO2)
Quartzite
Quartzite (primarily SiO2)
Ironstone Concretion
Ferruginous Concretion
Obsidian (Tumbled Apache Tear)
Volcanic Glass (SiO2)
Obsidian
Volcanic Glass (Silica / SiO2)
Obsidian
Obsidian (Volcanic glass, primarily SiO2)
Ironstone Concretion
Ferruginous Sandstone / Iron-rich Sedimentary Rock
Obsidian
Volcanic Glass (Amorphous silicon dioxide with trace impurities)
Golden Sheen Obsidian
Obsidian (volcanic glass) with inclusions of gas bubbles and mineral crystals (e.g., hematite, magnetite) causing the sheen
Lepidodendron Fossil (Scale Tree)
Lepidodendron sp.
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Concretion
Septarian Concretion (Clay-Ironstone Nodules)
Concretion with Quartz Veining
Septarian Concretion (CaCO3 / SiO2)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Ironstone Concretion (Limonite/Goethite)
Ferruginous Siltstone / Limonite Concretion (FeOO(OH)·nH2O)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities
Dumortierite Quartz
Al7(BO3)(SiO4)3O3
Ironstone Concretion (Siderite Nodules)
Siderite (FeCO3) in Mudstone or Sandstone matrix
Obsidian
Volcanic Glass (SiO2)
Apache Tears (Obsidian)
Hydrated Volcanic Glass (Amorphous SiO2 + H2O)
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Orange Quartz (Ferruginous Quartz)
Silicon Dioxide (SiO2) with Iron Oxide inclusions