Obsidian
Obsidian (Volcanic Glass)
igneous
Category
Non Geological
Browse non geological specimens identified by the Rock Identifier community.
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Snowflake Obsidian
Spherulitic Obsidian (Amorphous volcanic glass with Phenocrysts of Cristobalite)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
igneous
Obsidian
Volcanic Glass (70% or more SiO2)
igneous
Opalite
Opalescent Glass (SiO2 + coloring agents)
Mineral (Synthetic/Man-made)
Weathered ironstone concretion (probable limonite/goethite nodule)
Limonite-goethite-rich iron-oxide concretion; chiefly FeO(OH)·nH₂O
mineral
Schist with Garnet inclusions
Garnet-mica-schist
metamorphic
Concretion (likely iron-rich sandstone or claystone concretion)
Diagenetic carbonate/iron-oxide concretion; exact mineralogy requires testing
sedimentary
Iron-stained quartz-rich rock (likely ironstone/quartz vein material)
Quartz (SiO₂) with iron oxides/hydroxides, likely limonite/goethite; precise rock type cannot be confirmed visually
metamorphic
Black Obsidian
Obsidian (Amorphous volcanic glass, SiO2)
igneous
Black onyx or black agate bead bracelet
Microcrystalline quartz, chiefly chalcedony (SiO₂); commonly sold as black onyx, sometimes dyed black agate
gemstone
White Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Polished yellow-brown quartzite or jasper
Quartz-rich quartzite; possibly iron-stained jasper (microcrystalline SiO₂)
metamorphic
Tumbled green aventurine (likely)
Quartz (SiO₂) with fuchsite or other green mica inclusions
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Zebra Rock (Zebra Stone / Ribbon Stone)
Siltstone with Ferruginous Banding (Primarily Quartz, Kaolinite, and Hematite)
sedimentary
Sandstone pebble
Sandstone (arenite / quartzarenite)
sedimentary
Fossil bone or tooth fragment
Mineralized fossil vertebrate bone/tooth; exact taxon cannot be determined from the photograph
fossil
Quartzite
Quartzite (primarily SiO2)
metamorphic
Gold Ore (in Quartz/Sulfide matrix)
Native Gold (Au) in Quartz (SiO2) and Pyrite (FeS2)
mineral
Black Obsidian
Amorphous volcanic glass (SiO2)
igneous
Blue faceted gemstones, likely blue sapphire
Corundum (Al₂O₃), blue varieties colored chiefly by iron and titanium
gemstone
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Slag Glass (Cullet)
Amorphous Silicon Dioxide (SiO2) with metal oxide colorants
Anthropogenic (Man-made)
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Slag
Glassy silicate byproduct (anthropogenic material)
industrial byproduct
Common Opal (Potch)
Opal (Hydrated silica, SiO2·nH2O)
mineral
Likely tumbled orange carnelian
Carnelian, orange chalcedony (microcrystalline quartz, SiO₂)
gemstone
Quartzite with Garnet
Garnetiferous Quartzite (SiO2 + X3Y2(SiO4)3)
metamorphic
Snowflake Obsidian
Spherulitic Obsidian (Volcanic Glass with Cristobalite inclusions)
igneous
Asphalt (Aggregate)
Bituminous macadam / Concrete Aggregate
sedimentary
Amber
Resinite / Fossilized Tree Resin
mineral
Blue Goldstone
Aventurine Glass (Silicon Dioxide infused with Cobalt/Copper)
Synthetic (Man-made Glass)
Quartzite
Quartzite (primarily SiO2)
metamorphic
Acrylic or Resin (Synthetic Imitation)
Polymethyl Methacrylate (PMMA) or Polyepoxide
Synthetic/Man-made Polymer
Fine-grained gray stone, likely slate or weathered basalt
Indeterminate; possible slate (foliated phyllite-grade shale)
metamorphic
Iron-stained quartz/chert pebble
Microcrystalline quartz (SiO₂) with iron-oxide minerals, chiefly goethite/limonite
sedimentary
Snowflake Obsidian
Volcanic glass containing Cristobalite (SiO2)
igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Opalite
Man-made Opalized Glass (Synthetic Glass)
gemstone