Obsidian
Obsidian (Volcanic Glass)
Category
Browse organic (mineraloid) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass)
Snowflake Obsidian
Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
Golden Sheen Obsidian
Volcanic Glass (predominantly SiO2, >70%)
Limonite (Yellow Ochre)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
Snowflake Obsidian
Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)
Black Opal (Triplet)
Hydrated Silica (SiO2·nH2O)
Obsidian
Volcanic glass (silica-rich rhyolitic melt; primarily SiO₂)
Obsidian
Obsidian (Extrusive Volcanic Glass)
Obsidian
Volcanic Glass (comprised primarily of SiO2)
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
Mahogany Obsidian
Volcanic glass (SiO2 + Fe2O3)
Opalite
Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)
Obsidian
Volcanic glass (Amorphous silicon dioxide)
Obsidian
Volcanic glass
Mahogany Obsidian
Volcanic Glass (SiO2 with Fe/Mg oxides)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Common Opal (Potch)
Hydrated Silica (SiO2·nH2O)
Black Obsidian
Volcanic glass (Amorphous silicates)
Limonite with Quartz (Gossan)
Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)
White Opal (Common)
Hydrated Silica (SiO2·nH2O)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
Cantera Opal (Mexican Fire Opal in Rhyolite Matrix)
Hydrated amorphous silica in rhyolite (SiO2·nH2O in volcanic matrix)
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
Raw Amber / Resin Mineral
Succinite (Fossilized Tree Resin)
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Obsidian
Volcanic Glass (Amorphous silicon dioxide with trace impurities)
Limonite (Iron Ore)
Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)
Red Sandstone
Clastic Sedimentary Mineraloid (predominantly Quartz grains with Iron Oxide cement)
Pearls (likely freshwater cultured pearls)
Pearl: nacre, primarily aragonite (CaCO₃) with conchiolin
Amber and Citrine Quartz
Succinite (Amber) and Silicon Dioxide (SiO2 / Citrine)
Amber
Succinite (fossilized resin, C10H16O)
Amber
Succinicum (C10H16O)
Naga Silver-Inlaid Ebony and Bone/Horn Beads
Diospyros (Ebony) or Keratin (Horn) with Silver/White-Metal Inlay
Ironstone concretion / Limonitic Sandstone
Goethite/Hematite Cemented Sandstone (Hydrated Iron Oxide)
Amber
Resinite / Fossilized Tree Resin
Petrified Wood
Silicified wood (Quartz replacement, SiO2)
Limestone (specifically Bituminous or Carbonaceous Limestone)
Calcium Carbonate (CaCO3) with Organic Impurities
Chert (Agatized/Chalcedony variety)
Microcrystalline Quartz (SiO2)
Pyritic Shale
Carbonaceous Shale with Iron Pyrite (FeS2)
Fossiliferous Shale
Carbonaceous Shale (with potential plant/aquatic fossils)