Chert (within Limestone matrix)
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
Category
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Chert (within Limestone matrix)
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
Chert Nodule (with Geode cavity)
Cryptocrystalline Quartz (SiO2)
Amber
Succinite
Obsidian
Volcanic Glass (SiO2)
Chert (variations include Flint)
Silicon Dioxide (SiO2)
Amber
Succinite (organic fossilized resin)
Pink Opal
Hydrated Silica (SiO2·nH2O) with Palygorskite inclusions
Clear Quartz
Silicon Dioxide (SiO2)
Diamond in Kimberlite
Diamond (C in Kimberlite Matrix)
Banded River Cobble with Mafic Dike
Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion
Polished black stone, likely black obsidian
Obsidian (volcanic glass), chiefly silica-rich rhyolitic composition
Black Obsidian
Volcanic Glass (SiO2 + MgO / Fe3O4)
Chert (variant of Flint)
Chert (SiO2)
Agate Geode with Quartz
Silicon Dioxide (SiO2)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Sandstone
Sedimentary Clastic Rock (Quartzose Sandstone)
Geode with Quartz and Chalcedony
Silicon Dioxide (SiO2)
Sandstone with Quartz Vein
Arenite with SiO2 intrusion
Iron Slag
Ferrous Slag (Industrial Byproduct)
Slag (Industrial Glass/Metal Waste)
Artificial silicate/ferro-silicate byproduct
Banded Calcite (often sold as 'Mexican Onyx' or 'Green Onyx')
Calcite (Calcium Carbonate, CaCO3)
Chert (variations include Flint/Novaculite)
Chert (formula: SiO2)
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Chert (Pink Chert/Jasper)
Cryptocrystalline Quartz (SiO2)
Fossil Assortment and Geological Specimens
Various (including Ammonoidea)
Quartz-veined Limestone
Sedimentary limestone with quartz/calcite veinlets
Limonite (Iron-rich Siltstone / Sandstone base)
Hydrous ferric oxide mixture (FeO(OH)·nH2O)
Chert (Jasper variation)
Silicon Dioxide (SiO2)
Fossiliferous Sandstone Pebble (with Crinoid / Shell Impression)
Sandstone containing fossiliferous inclusions (SiO2 matrix with calcite/silica cast fossil)
Chert (Jasper variation)
Silicon dioxide (SiO2)
Small brown-gray mineral fragment
Indeterminate; possibly weathered quartz-, feldspar-, or iron-oxide-bearing rock
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Ferrosilicon Slag (Industrial Vitrified Glass)
Vitreous Silicate Residue
Quartz Mineral
Silicon Dioxide (SiO2)
Snowflake Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite/Magnetite inclusions), SiO2
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)
Polished mahogany obsidian (likely)
Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), with iron oxides
Limonite/Goethite nodule
Goethite (FeO(OH)) with Hydrated Iron Oxides
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Obsidian
Volcanic glass (high silica volcanic rock)
Banded Gneiss Pebble
Banded Gneiss