Opalite
Synthetic Glass (Silica-based)
Category
Browse mineraloid (impact glass) specimens identified by the Rock Identifier community.
Opalite
Synthetic Glass (Silica-based)
Tektite (Indochinite)
Tektite (Amorphous Meteoritic Glass)
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Obsidian
Volcanic Glass (SiO2 + impurities)
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Moonstone
Adularia or oligoclase feldspar, commonly showing adularescence
Quartzite River Rock
Metamorphic Quartzite (SiO2)
Milky quartz
Quartz (silicon dioxide, SiO₂)
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite/Magnetite inclusions), SiO2
Obsidian
Volcanic Glass (70-75% SiO2 with MgO and Fe3O4)
Moldavite
Tektite (Natural Silica Glass)
Sea Glass (Frosted Quartz/Glass)
Amorphous Silicon Dioxide (SiO2)
Cullet Glass (Slag)
Amorphous Silicon Dioxide (Man-made)
Flint or chert
Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities
Quartz Pebble (River Agate / Chalcedony)
Silicon Dioxide (SiO2)
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Tumbled blue chalcedony
Chalcedony, microcrystalline quartz (SiO₂)
Black Obsidian
Volcanic Glass (Amorphous SiO2 with trace impurities)
Pyrite (Fool's Gold)
Iron Pyrite (FeS2)
Fulgurite
Fulgurite (Lechatelierite)
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (SiO2) with metallic oxide impurities
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite/Magnetite inclusions)
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (primarily SiO2)
Quartz Pebble
Silicon Dioxide (SiO2)
Mahogany Obsidian
Volcanic Glass (Silicate: SiO2 + Fe2O3)
Obsidian
Volcanic Glass (predominantly SiO2)
Cobalt Glass Slug (Cullet)
Man-made Silicate Glass with Cobalt Oxide (CoO)
Tumbled black stone, likely black obsidian
Obsidian — volcanic glass, primarily SiO₂
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (Industrial Byproduct)
Obsidian
Volcanic Glass (SiO2)
Obsidian (Gold Sheen)
Obsidian (SiO2 + impurities)
Cobalt Glass Slug (Man-made Glass)
Amorphous Silica with Cobalt Oxide (SiO2 + CoO)
Dragon's Breath (Mexican Opal Glass)
Artisan Foil Glass (SiO2 based)
Obsidian
Volcanic Glass (Amorphous SiO2)
Moldavite
Moldavite (Silica-rich glass, SiO2 + Al2O3)
Obsidian
Obsidian
Polished mahogany obsidian (probable)
Volcanic glass; chiefly rhyolitic silica-rich glass (SiO₂), compositionally near rhyolite
Cullet Glass (Man-made Glass Slag)
Amorphous Silica (SiO2) with chemical additives
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
Cullet (Slag Glass)
Amorphous Silica (Industrial byproduct)
Polished black stone, likely black obsidian
Obsidian (volcanic glass), primarily rhyolitic silica glass
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)