Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Category
Non Geological
Browse non geological specimens identified by the Rock Identifier community.
Learn about Non Geological in the encyclopedia
View all →
Slag Glass
Vitreous Silicate Residue
industrial byproduct (anthropogenic rock)
Banded Sandstone (Liesegang Rings)
Sedimentary sandstone with Iron oxide precipitates
sedimentary
Obsidian
Obsidian (Volcanic Glass, complex silicate)
igneous
Quartz with Mica inclusions (Gold-colored Mica)
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (Phlogopite/Muscovite) inclusions
Mineral
Rough Green Beryl (Emerald variety)
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)
mineral
Cupronickel (on a 1981 Mexico 20 Pesos coin)
Copper-Nickel Alloy (Cu75Ni25)
mineral
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide , SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Limonite (Yellow Ochre)
Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)
mineral
River Siltstone / Mudstone Pebble
Siltstone (composed of mixed silicate and carbonate minerals)
sedimentary
Concrete rubble
Anthropogenic conglomerate
sedimentary
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Slag (Industrial Glass)
Artificial Vitreous Silicate
mineraloid (anthropogenic)
Obsidian
Volcanic Glass (SiO2 dominant)
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Cullet Glass (Slag)
Amorphous Silicon Dioxide (Man-made)
Mineraloid
Snowflake Obsidian
Volcanic glass (SiO2) with Cristobalite (SiO2) inclusions
igneous
Red Jasper
Microcrystalline Quartz (SiO2) with Hematite impurities
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Obsidian
Amorphous volcanic glass (70-75% SiO2)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Pink Quartzite
Quartzite (SiO2)
metamorphic
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Quartzite
Metamorphic Quartzite
metamorphic
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
igneous
Blue faceted gemstones, likely blue sapphire
Corundum (Al₂O₃), blue varieties colored chiefly by iron and titanium
gemstone
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Ironstone Concretion
Ironstone (Siderite/Goethite/Hematite matrix)
sedimentary
Tumbled green aventurine (likely)
Quartz (SiO₂) with fuchsite or other green mica inclusions
mineral
Obsidian
Volcanic glass (SiO2 - Silicon dioxide predominant composition)
Igneous
Obsidian
Volcanic Glass (70-75% SiO2)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Asphalt (Aggregate)
Bituminous macadam / Concrete Aggregate
sedimentary
Blue Slag Glass
Man-made Silicon Dioxide (Amorphous)
Anthropogenic (Man-made)
Black Obsidian
Amorphous volcanic glass (SiO2)
igneous
Limestone with Chert Nodule
Carbonate rock (CaCO3) with Microcrystalline Silicon Dioxide (SiO2) inclusion
sedimentary
Drill Core Sample
Cylindrical Rock Core (Specific mineralogy varies by extraction site)
Metamorphic (Likely Gneiss or Schist based on texture)