Possible tektite or dark volcanic rock fragment
Uncertain; likely natural silicate glass (tektite) or basalt
mineral
Category
Mineraloid (Impact Glass)
Browse mineraloid (impact glass) specimens identified by the Rock Identifier community.
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Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
mineraloid / sedimentary (secondary formation)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Moldavite
Tektite (Natural Silicate Glass)
gemstone
Polymict breccia (likely impact breccia)
Polymict lithic breccia; composition appears basaltic/mafic clasts in a dark, fine-grained matrix
igneous
Glass
Amorphous Silicon Dioxide (SiO2)
mineraloid
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
igneous
Tektite (Indochinite)
Tektite (SiO2 + Al2O3, Glassy Melts)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Tektite (Indochinite)
Tektite (High-silica natural glass)
igneous
Likely translucent quartz/chalcedony fragment
Silicon dioxide (SiO₂), probably microcrystalline quartz or quartz
mineral
Chert (Flint)
Chert (SiO2)
sedimentary
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70–75% SiO2)
igneous
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
igneous
Tektite (Indochinite)
Tektite (Natural silica glass)
meteorite
Quartzite River Rock
Quartzite (primarily SiO2)
metamorphic
Snowflake Obsidian
Volcanic Glass with Cristobalite Inclusions
igneous
Purple fluorite cluster
Fluorite (calcium fluoride, CaF₂)
mineral
Green obsidian (likely moldavite)
Natural volcanic glass; if extraterrestrial-impact glass, moldavite (tektite)
gemstone
Black Obsidian
Volcanic glass
igneous
Obsidian
Volcanic Glass
igneous
Chert Pebble (Flint)
Microcrystalline/Cryptocrystalline Quartz (SiO2)
sedimentary
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (70–75% SiO2)
Igneous
Libyan Desert Glass
Impactite silica glass (SiO2)
tektite (impact glass)
Snowflake Obsidian
Volcanic Glass (SiO2) with Cristobalite inclusions
igneous
Obsidian
Volcanic glass
igneous
Moldavite
Tektite (Silica Glass - SiO2 + Al2O3, FeO, MgO, CaO, Na2O, K2O)
gemstone
Black Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Obsidian
Volcanic glass
igneous
Tumbled tektite (likely Indonesian or Philippine tektite)
Natural silica-rich impact glass; chiefly SiO₂ with minor Al₂O₃, FeO, MgO, CaO, and Na₂O
meteorite
Black Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70-75% SiO2)
igneous
Quartz River Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Snowflake Obsidian
Obsidian with Spherulitic Cristobalite (SiO2)
igneous
Tektite (Indochinite)
Tektite (High-silica natural glass)
mineralogical glass/meteorite impactite
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)
igneous
Snowflake Obsidian
Volcanic glass (SiO2) with Cristobalite (SiO2) inclusions
igneous
Tektite (Indochinite)
Tektite (Amorphous Silica Glass), SiO2(Al2O3)
igneous
Quartzite River Cobble
Quartzite (primarily SiO2)
metamorphic
Opalite
Man-made Glass (Synthetic Opalized Glass)
gemstone