Obsidian
Obsidian (principally SiO2)
igneous
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Learn about Amorphous Solid in the encyclopedia
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Tektite (Indochinite)
Tektite (High-silica natural glass, primarily SiO2 with Al2O3)
igneous
Concretion
Sedimentary Concretion (e.g., Siderite or Ironstone)
sedimentary
Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
mineral
Amber
Succinite (fossilized resin)
mineral
Ironstone Concretion
Siderite or Hematite Concretion
sedimentary
Ambergris
Ambergris (Coprolite-adjacent/Organic secretion)
mineraloid
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrous ferric oxide)
mineral
Limonite with Opal infusion
FeO(OH)·nH2O (Limonite) / SiO2·nH2O (Opal)
mineral
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Obsidian
Obsidian (volcanic glass; primarily SiO2)
igneous
Chrysocolla
Hydrated copper silicates (Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Coal (specifically Bituminous or Anthracite)
Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N
sedimentary
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Dendritic Opal
Hydrated Silica with Manganese inclusions (SiO2·nH2O)
mineral
Coquina
Biogenic Limestone
sedimentary
Amber
Succinite (Resinite), C10-H16-O
mineral
Amber
Succinite (fossilized tree resin)
mineraloid / sedimentary organic material
Obsidian
Volcanic Glass (Extrusive Igneous Rock, primarily SiO2)
igneous
Ambergris (Sea Wax)
Physeter macrocephalus fecalith
Organic geological/oceanic specimen
Obsidian and Green Calcite
Volcanic Glass and Calcium Carbonate (CaCO3)
igneous and sedimentary/mineral
Gastropod Fossil (Snail Stone or Steinkern)
Class Gastropoda (Calcium Carbonate - CaCO3 / Silica - SiO2 replacing original shell)
sedimentary
Chrysocolla in Matrix
Chrysocolla (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O)
mineral
Anthracite Coal
Anthracite
metamorphic
Anthracite Coal
Anthracite coal (High-rank coal)
sedimentary
Amber
Succinite (specifically for Baltic amber); approximate formula C10H16O
organic mineraloid
Limonite (Oxidized Iron Ore)
FeO(OH)·nH2O (Hydrous ferric oxide)
mineral
Bauxite
Bauxite (Mixture of Hydrous Aluminum Oxides)
sedimentary
Opalite (Synthetic Opalized Glass)
Synthetic Silicon Dioxide (SiO2) glass
mineral
Quartz / Common Opal
Silicon Dioxide (SiO2)
mineral
Ferrosilicon Slag (Industrial Vitrified Glass)
Vitreous Silicate Residue
Antropogenic (Man-made industrial byproduct)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Amber
Succinite (Fossilized Tree Resin) - C10H16O
mineral
Snowflake Obsidian
Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)
igneous
Apache Tear
Hydrated Obsidian (Volcanic Glass)
Igneous
Coquina / Shelly Limestone
Bioclastic Limestone (composed of CaCO3)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)
igneous
Snowflake Obsidian
Obsidian with Cristobalite inclusions (70-75% SiO2)
igneous
Scoria (Lava Rock)
Scoria (extrusive volcanic rock)
igneous