Green Calcite (Onyx Marble)
Carbonate mineral (Calcium Carbonate, CaCO3)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Green Calcite (Onyx Marble)
Carbonate mineral (Calcium Carbonate, CaCO3)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Snowflake Obsidian (Tumbled)
Obsidian with Cristobalite inclusions
Obsidian
Obsidian (Volcanic Glass)
Polished tektite (likely indochinite)
Natural silica-rich impact glass; mainly SiO₂ with Al₂O₃, FeO, MgO, CaO, and Na₂O
Cannonball Concretion
Calcite-cemented Sandstone Concretion
Banded Sandstone Peabble
Arenite with iron oxide banding
Obsidian
Volcanic Glass (predominantly SiO2)
Sandstone with Dendritic Manganese Oxides
Sandstone (SiO2 predominant) with Oxide Dendrites (MnO2)
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Volcanic Glass (70-75% SiO2)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Obsidian
Volcanic Glass (SiO2)
Green Aventurine
Aventurine Quartz (SiO2 with inclusions of Fuchsite mica)
Obsidian
Volcanic Glass (Amorphous SiO2)
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)
Black obsidian (possibly industrial glass or slag)
Volcanic glass; predominantly rhyolitic composition, chiefly SiO₂
Ironstone Concretion (Boxwork)
Siderite-Limonite Concretion (FeO(OH)·nH2O)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Polished mahogany obsidian
Volcanic glass; rhyolitic obsidian (SiO₂-rich, amorphous)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2)
Sandstone Chert Concretion
Silica-cemented Concretion (primarily SiO2)
Concretion with Geode Cavity
Ferruginous Sandstone Concretion with Quartz Center
Obsidian (Apache Tear)
Volcanic Glass (High-silica Rhyolite)
Ironstone Concretion
Siderite or Goethite Concretion
Dalmation Jasper
Perthitic Feldspar with Arfvedsonite inclusions
Obsidian
Amorphous volcanic glass (SiO2)
Obsidian
Volcanic Glass (SiO2)
Snowflake Obsidian
Volcanic glass containing Spherulites (SiO2)
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Horse Chestnut (Buckeye seed)
Aesculus hippocastanum seed
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Ferruginous Quartz (Iron-stained Quartz)
Quartz with Iron Oxide inclusions (SiO2 with 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)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Pyrite
Iron Disulfide (FeS2)