Obsidian
Volcanic Glass (Amorphous silicon dioxide with impurities)
Category
Browse organic mineraloid specimens identified by the Rock Identifier community.
Obsidian
Volcanic Glass (Amorphous silicon dioxide with impurities)
Black Obsidian
Volcanic glass
Obsidian
Volcanic Glass
Obsidian
Volcanic Glass (SiO2 + impurities)
Fulgurite
Fulgurite (Lechatelierite)
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Tumbled black stone, likely black obsidian
Obsidian — volcanic glass, primarily SiO₂
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)
Amber
Succinite (Resinite)
Obsidian
Volcanic glass
Limonite (Ironstone)
Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
White Opal
Hydrated Silica (SiO2·nH2O)
Obsidian
Volcanic Glass (Amorphous SiO2)
Obsidian
Volcanic Glass (SiO2 rich)
Polished mahogany obsidian (probable)
Volcanic glass; chiefly rhyolitic silica-rich glass (SiO₂), compositionally near rhyolite
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Amber
Succinite (specifically for Baltic amber); Approximate formula: C10H16O
Obsidian
Volcanic Glass (70% or more SiO2)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Obsidian (Amorphous volcanic glass, predominantly SiO2)
Obsidian
Volcanic glass
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Green Opal
Hydrated Silica (SiO2·nH2O)
Pearl (Biogenic Mineraloid)
Calcium carbonate (CaCO3) primarily as Aragonite
Precious Opal
Hydrated Silica (SiO2·nH2O)
Limonite/Ironstone
Limonite (FeO(OH)·nH2O)
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurity)
Limonite (Iron Ore)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
Likely obsidian (possibly tektite or slag glass)
Volcanic glass; primarily SiO₂, noncrystalline
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Jet
Lignite (Anthracite-grade compact coal)
Obsidian
Volcanic Glass (SiO2)
Obsidian (black volcanic glass), possibly slag or basalt
Obsidian; chiefly amorphous volcanic silica glass, approximately SiO₂-rich rhyolitic composition
Opal
Hydrated Silica (SiO2·nH2O)
Limonite (Ironstone)
Limonite (mixture of hydrated iron(III) oxide-hydroxides)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Opal (in Jewelry Setting)
Hydrated Silicon Dioxide (SiO2·nH2O)
Opal
Hydrated Amorphous Silica (SiO2·nH2O)