Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
igneous
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Slag (Industrial Glassy Byproduct)
Anthropogenic silicate byproduct (Slag)
Mineral-like byproduct (often mistaken for igneous rock or meteorite)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Obsidian with Spherulitic Devitrification (Snowflake Obsidian/Mahogany related)
Volcanic Glass (70% or more SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
sedimentary
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated Iron Oxide)
mineral
Obsidian
Volcanic Glass (SiO2 rich)
igneous
Amber
Organic gemstone (Succinite is common if from the Baltic)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Coal (Anthracite)
Anthracite (Carbon-based organic sedimentary/metamorphic rock)
metamorphic
Slag
Glassy silicate byproduct (anthropogenic material)
industrial byproduct
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Obsidian
Volcanic Glass (Primary component: SiO2)
igneous
Ironstone Concretion
Siderite or Limonite Concretion
sedimentary
Limonite with Quartz (Gossan)
Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)
Mineral
Amber
Succinite (a common variety of fossilized resin)
mineral
Dendritic Opal
Dendritic Common Opal (SiO2·nH2O with Manganese oxide inclusions)
mineral
Tektite (Indochinite)
Tektite (Silica-rich natural glass)
mineral
Obsidian
Obsidian (Volcanic glass), 70-75% SiO2
igneous
Chrysocolla in Matrix
Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Silicate/Secondary Copper Mineral)
mineral
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Obsidian
Obsidian (Extrusive Volcanic Glass)
igneous
Amber
Succinite (specifically for Baltic amber); chemical formula approx. C10H16O
Organic Gemstone (fossilized resin)
Human Skin (Epidermis/Dermis)
Integumentary tissue (High content of hydroxyapatite in bones, though the surface is biological)
Mineral-like biological tissue
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Conglomerate
Conglomerate (SiO2 dominant in clasts)
sedimentary
Opal
Hydrated silica (SiO2·nH2O)
mineraloid
Amber
Succinite
mineral
Tiffany Stone
Fluorite Opal (a complex mix of Fluorite, Opal, Calcite, Dolomite, Quartz, and Bertrandite)
mineral
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Pumice
Pumice (Vesicular Rhyolite/Andesite)
igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide)
Igneous
Pumice
Vesicular volcanic glass (primarily SiO2)
igneous
Ironstone Concretion (Moqui Marble)
Iron Oxide Concretion (Fe2O3 / FeO(OH) mixed with SiO2)
sedimentary
Limonite (Pseudomorph after Pyrite/Marcasite)
Hydrated Iron Oxide (FeO(OH)·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with Hematite/Magnetite inclusions)
igneous
Obsidian
Obsidian (Volcanic glass), SiO2 (major component)
igneous
Mahogany Obsidian
Volcanic Glass with Hematite or Magnetite inclusions (SiO2 + Fe2O3)
igneous
Ferro-slag (Leland Blue/Slag Glass)
Anthropogenic Vitreous Silica (Industrial Slag)
igneous
Anthracite Coal
Anthracite
metamorphic
Baltic Amber (Butterscotch or Egg Yolk Variety)
Fossilized Tree Resin (Succinite); Approximate formula: C10H16O
Organic Gemstone (Succinite)