Obsidian (Apache Tear)
Volcanic Glass (composed mainly of SiO2)
igneous
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Amber
Succinicum (Organic Gemstone - Resinite)
mineraloid
Obsidian
Obsidian (principally SiO2)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Pumice
Pumice (a highly vesicular volcanic glass)
igneous
Opalite
Man-made Glass (SiO2 + additives)
mineraloid (synthetic)
Sandstone Geode (Unbroken)
Siliciclastic sedimentary rock (primarily Quartz)
sedimentary
Tektite (Indochinite)
Tektite (High-silica impact glass)
mineraloid
Obsidian
Volcanic glass (high silica content, usually >70% SiO2)
igneous
Dendritic Limestone
Calcite with Manganese Oxide (Manganese Dendrites)
sedimentary
Apache Tear
Obsidian (Hydrated Volcanic Glass - SiO2)
igneous
Iron Slag
Vitreous glassy waste (Fe-Si-Al-Ca compounds)
Mineral byproduct (anthropogenic / techno-fossil)
Conglomerate
Conglomerate (Clastic sedimentary rock)
sedimentary
Obsidian
Obsidian (Volcanic Glass, SiO2 dominated)
igneous
Pink Opal
Hydrated Silica (SiO2·nH2O) with Palygorskite inclusions
Mineraloid
Obsidian
Obsidian (principally SiO2 - Silicon Dioxide)
igneous
Slag (Industrial Glassy Byproduct)
Ferro-silicate Slag
Anthropogenic / Non-Natural
Chrysocolla Chalcedony
Hydrated Copper Phyllosilicate (Cu,Al)2H2Si2O5(OH)4 + SiO2
mineral
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
igneous
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (70–75% SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Rough Precious Opal
Hydrated Silica (SiO2·nH2O)
mineral
Ironstone Concretion
Siderite or Hematite-bonded Concretion
sedimentary
Desert Varnish (on Sandstone)
Rock Varnish (composed of Manganese oxides, Iron oxides, and Clay minerals)
sedimentary
Petrified Wood
Silicified wood (Quartz, SiO2)
metamorphic
Ironstone Concretion (Moqui Marble)
Ironstone concretion (Fe2O3 with a sandstone core)
sedimentary
Tektite (specifically Indochinite)
Tektite (Natural silica glass)
Mineraloid (Impact glass)
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
igneous
Ironstone with Pyrite
Ferruginous Sandstone (Fe2O3) with minor Sulfide minerals (FeS2)
sedimentary
Ironstone Concretion (Moqui Marble type)
Ferruginous Concretion (Fe2O3 / FeO(OH))
sedimentary
Bauxite
Bauxite (Al2O3·2H2O)
sedimentary
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
igneous
Opalite (a synthetic glass)
Silicon Dioxide (SiO2) with various additives; not a true mineral but a man-made gem simulant
Mineral Simulant (Synthetic Glass)
Pumice
Pumicite (fine-grained pumice), Scoria (similar origin but denser and darker, usually basaltic)
Igneous
Mixed Tumbled Stones Collection
Mixed Silicates and Carbonates (Quartz, Amorphous Silica, Carbonates)
multiple
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix
Metamorphic or Igneous (context dependent)
Amber
Succinite (with formula approximately C10H16O)
Organic mineraloid
Fulonite (Fulgurite-like)
Fulgurite (SiO2 fused silica/lechatelierite)
Metamorphic (Pseudo-igneous)
Amber (Dark/Black Variety)
Succinite (Resinite), C10H16O
mineral
Man-made Crystal (Lead Glass)
Lead oxide-doped Silica Glass (approx. SiO2 + PbO)
Mineraloid/Synthetic Material
Ferruginous Sandstone with Ironstone Concretion
Goethite-rich Sandstone (FeO(OH))
sedimentary
Slag (Industrial)
N/A (Anthropogenic Slag)
industrial by-product