Obsidian (black volcanic glass)
Obsidian; primarily amorphous SiO₂-rich rhyolitic glass
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Obsidian (black volcanic glass)
Obsidian; primarily amorphous SiO₂-rich rhyolitic glass
Obsidian flake
Volcanic glass; primarily silica-rich rhyolitic composition (approximately SiO₂)
Dioptase
Dioptase (CuSiO2(OH)2)
Pyrite
Iron Disulfide (FeS2)
Ironstone Concretion / Limonite
Goethite and Limonite (FeO(OH)·nH2O)
Limonite Concretion (Goonie or Rattlestone)
Limonite (FeO(OH)·nH2O)
Mahogany Obsidian
Volcanic glass (Silicon Dioxide with Hematite/Magnetite inclusions)
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Obsidian
Obsidian (volcanic glass)
Black Tourmaline
Schorl (Na(Fe2+)_{3}Al_{6} (BO_{3})_{3} (Si_{6}O_{18})(OH)_{4})
Green Quartzite (Tumbled)
Metamorphosed Quartz-rich Sandstone
Ferruginous Sandstone with Concretion
Sandstone (SiO2 dominated with Fe2O3 cement)
Blue Quartz (specifically Dumortierite Quartz)
Silicon Dioxide (SiO2) with inclusions of Dumortierite (Al7BO3(SiO4)3O3)
Obsidian
Obsidian (principally SiO2/Silicon dioxide)
Blue Quartz (Dumortierite Quartz)
SiO2 containing inclusions of Dumortierite [Al7(BO3)(SiO4)3O3]
Ironstone Concretion
Limonitic/Hematitic Concretion
Black Obsidian
Volcanic Glass (predominantly SiO2)
Aventurine
Aventurine Quartz (SiO2 with inclusions)
Obsidian
Volcanic Glass (70% or more SiO2)
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
Horse Chestnut (Buckeye seed)
Aesculus hippocastanum seed
Apache Tear
Obsidian (Natural volcanic glass)
Quartzite
Quartzite (SiO2)
Blue Apatite
Apatite, Ca5(PO4)3(F,Cl,OH)
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
Obsidian
Volcanic Glass (SiO2 rich)
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
Diorite
Phaneritic Intermediate Igneous Rock
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
Goethite / Limonite Concretion
Iron Hydroxide Oxide (FeO(OH))
Blue Quartzite
Blue Quartzite (Primary mineral: Quartz, SiO2 with magnesio-riebeckite or crocidolite inclusions)
Polished Black Obsidian
Volcanic Glass (70-75% SiO2)
Snowflake Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)
Quartzite
Quartzite (SiO2)
Ferruginous Sandstone (Gozzan/Ironstone)
Arenite with Limonite/Goethite cement (FeO(OH)·nH2O)
Rhodonite
Manganese Silicate (Mn,Fe,Mg,Ca)SiO3
Chrysoprase
Silicon dioxide with nickel impurities (SiO2 + Ni)
Ironstone Nodule (Ironstone Concretion)
Siderite-rich Mudstone (FeCO3) or Limonite (FeO(OH)·nH2O)
Dendritic Opal
Opalized Chalcedony with Manganese Inclusions (SiO2 · nH2O)
Green glass sphere/marble
Soda-lime glass (primarily SiO2, Na2O, CaO)