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)
Snowflake Obsidian (Tumbled)
Obsidian with Cristobalite inclusions
Red Obsidian
Volcanic Glass (Amorphous SiO2)
Sandstone with Liesegang Rings
Quartzose Sandstone with Iron Oxide Precipitation
Ironstone Concretion
Siderite or Hematite Concretion
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)
Coal
Carbonaceous sedimentary rock
Sulfur
Native Sulfur (S)
Ironstone Concretion
Siderite or Ferruginous Concretion (FeCO3 or Iron Oxides)
Snowflake Obsidian
Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)
Metallic iron meteorite fragments (probable)
Iron meteorite, chiefly kamacite (α-(Fe,Ni)) with possible taenite
Obsidian
Volcanic glass (SiO2 - Silicon dioxide predominant composition)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2)
Obsidian
Obsidian (principally SiO2 - Silicon Dioxide)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Sodalite and Calcite
Na8(Al6Si6O24)Cl2 (Sodalite) and CaCO3 (Calcite)
Obsidian
Obsidian (Volcanic Glass, ~70% SiO2)
Banded Calcite (often sold as "Peaches and Cream" or "Orange Calcite")
Calcium Carbonate (CaCO3)
Sandstone Concretion
Ferruginous Sandstone Concretion
Quartz
Silicon Dioxide (SiO2)
Sandstone Concretion
Carbonate-cemented Sandstone Concretion
Ironstone Concretion (Pot Stone)
Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)
Sandstone (Wonderstone)
Clastic Sedimentary Rock (primarily SiO2)
Obsidian
Obsidian (Volcanic Glass, SiO2)
Boxwork Siderite or Sepatarian Nodule Weathering
Siderite (FeCO3) with secondary mineralization or Boxwork Geode fragment
Obsidian
Volcanic Glass
Obsidian
Volcanic Glass (SiO2 + impurities)
Variscite in Matrix (often traded as Wardite or Cryptocrystalline Variscite)
Variscite (AlPO4·2H2O)
Chert (Flint)
Chert (SiO2)
Tiffany Stone
Bertrandite Fluorite (CaF2 + Be4Si2O7(OH)2)
Scoria with Calcite Infills
Vesicular Basalt with secondary Calcification (CaCO3)
Concretion
Calcareous/Siliceous Concretion
Pyrite
Iron Disulfide (FeS2)
Obsidian
Amorphous volcanic glass (70-75% SiO2)
Siltstone
Siltstone (SiO2, Fe2O3, Al2O3 mix)
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Yellow Aventurine
Silicon Dioxide with inclusions (SiO2)
Quartz (Iron-stained or Milky)
Silicon Dioxide (SiO2)
Green Aventurine
SiO2 (Silicon Dioxide with Fuchsite inclusions)
Quartz Geode
Silicon Dioxide (SiO2)
Green Aventurine
Silicon Dioxide (Quartz with Fuchsite inclusions) - SiO2
Obsidian (likely black obsidian)
Volcanic glass; chiefly silica-rich rhyolitic composition, approximately SiO₂ 70–75%