Obsidian
Obsidian (Volcanic Glass, SiO2 > 70%)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass, SiO2 > 70%)
Green Aventurine (Green Quartzite)
Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)
Jasper with Manganese Dendrites
Silicon Dioxide (SiO2) with Oxide Mineral Inclusions
Quartz with Chalcopyrite
Silicon Dioxide (SiO2) with Copper Iron Sulfide (CuFeS2)
Liesegang Banded Sandstone (Wonderstone)
Ferruginous Sandstone with Liesegang Rings
Specular Hematite (Specularite)
Iron Oxide (Fe2O3)
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)
Scoria (Basaltic Lava Rock)
Vesicular Basalt
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Blue Apatite
Apatite group (Ca5(PO4)3(F,Cl,OH))
Green Quartzite Pebble
Quartzite (SiO2 with chlorite/fuchsite inclusions)
Green Aventurine
Silicon dioxide (SiO2) with inclusions of Fuchsite mica
Jasper with Dendritic Inclusions
Microcrystalline Quartz (SiO2) with manganese or iron oxide inclusions
Fossilized Nut / Coprolite / Concretion
Trace Fossil / Permineralized Plant Material
Fossil Brachiopod
Phylum Brachiopoda
Obsidian (likely snowflake-free black volcanic glass)
Volcanic glass; predominantly rhyolitic silica melt (SiO₂-rich, noncrystalline)
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Blue Quartz (specifically Dumortierite Quartzite)
Silicon Dioxide (SiO2) with inclusions of Dumortierite (Al7BO3(SiO4)3O3)
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
Likely polished dark stone or mineral specimen (unidentifiable from image)
Undetermined; possibly dark quartz-rich material, basalt, or obsidian
Granite with Pyrite Inclusion
Granite (felsic intrusive igneous rock) with Iron Sulfide (FeS2)
Ironstone Concretion (Limonite/Goethite)
Goethite-rich Concretion (FeO(OH))
Black Tourmaline
Schorl (Na(Fe2+)_{3}Al_{6} (BO_{3})_{3} (Si_{6}O_{18})(OH)_{4})
Scoria (Lava Rock)
Scoria
Quartzite Countertop
Quartzite (SiO2 dominated)
Trace Fossil (Lichenandites or Rhynie Chert Chert with Microfossils)
Trace fossil in microcrystalline quartz (SiO2)
Sandstone (with manganese staining)
Clastic sedimentary rock (primarily SiO2)
Black Onyx
Silicon Dioxide (SiO2)
Ferruginous Quartz
Silicon Dioxide (SiO2) with iron oxide inclusions
Greenstone (Celadonite-bearing Volcanic)
Hydrothermally altered basalt or andesite with Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2)
Obsidian
Volcanic Glass (70% or more SiO2)
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Black obsidian
Volcanic glass; predominantly silica-rich, noncrystalline SiO₂
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities
Banded Sandstone
Arenite with Liesegang banding
Green Aventurine
Silicon Dioxide with Fuchsite inclusions (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)
Snowflake Obsidian (Flower Jasper variant)
Vitreous volcanic silicate with cristobalite inclusions
Sodalite
Na8(Al6Si6O24)Cl2
Sandstone (Banded)
Clastic Sedimentary Rock (primarily Quartz, SiO2)
Ironstone Concretion
Siderite or Hematite-bonded Concretion
Blue Apatite
Fluorapatite (Ca5(PO4)3F)