Ironstone Concretion (Limonite/Goethite)
Ironstone (primarily FeO(OH)·nH2O)
sedimentary
Category
Industrial Byproduct (Often Mistaken For Obsidian Or Mineral)
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
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Obsidian flake
Volcanic glass; primarily silica-rich rhyolitic composition (approximately SiO₂)
igneous
Dumortierite Quartz (Blue Quartz)
Al7(BO3)(SiO4)3O3 / Quarz with Dumortierite inclusions
mineral
Sandstone Concretion
Clastic Sedimentary Rock (primarily SiO2 with mineral cement)
sedimentary
Sandstone with Ironstone Concretion
Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))
sedimentary
Obsidian
Volcanic Glass (SiO2 with impurities)
igneous
Milky Quartz (Stained with Iron)
Silicon Dioxide (SiO2)
mineral
Chert Concretion
Sedimentary Cryptocrystalline Quartz (SiO2)
sedimentary
Yellow Quartzite or Yellow Jasper
Quartzite (primarily SiO2 with Iron oxide staining)
metamorphic
Rough Sodalite
Sodalite, Na8(Al6Si6O24)Cl2
mineral
Sodalite
Na8(Al6Si6O24)Cl2
mineral
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Obsidian
Volcanic Glass (SiO2)
igneous
Siltstone
Siltstone (primarily SiO2 with Al2O3)
sedimentary
Green Quartzite / Aventurine
Quartzite (SiO2 with fuchsite/chlorite inclusions)
metamorphic
Obsidian (Blue)
Volcanic Glass (SiO2)
igneous
Boxwork or Septarian Concretion
Septarian nodule / Boxwork weathering
sedimentary
Sodalite in Matrix (often called Blue Marble or Sodalite-Syenite)
Sodalite-bearing Syenite / Na8Al6Si6O24Cl2 (Sodalite component)
igneous
Bismuth Crystal
Bismuth (Bi)
mineral
Ironstone Concretion (Desert Varnish / Hematite-Goethite Nodule)
Iron oxide / hydroxide deposit (predominantly Fe2O3 and FeO(OH))
sedimentary
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
Amazonite
KAlSi3O8 (Potassium Feldspar, variety of Microcline)
Mineral
Chalcopyrite in River Pebble (Pebble with Pyrite/Fool's Gold inclusions)
CuFeS2 in fine-grained igneous host rock (Basalt / Andesite)
igneous
Obsidian
Volcanic Glass (Amorphous silicon dioxide with impurities)
igneous
Dioptase
Dioptase (CuSiO3 · H2O)
mineral
Ferruginous Quartz (Iron-stained Quartz)
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
mineral
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Apache Tear (Obsidian)
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Obsidian (likely black obsidian)
Volcanic glass, predominantly rhyolitic to dacitic silica-rich melt; approximate composition ~70–75% SiO₂
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite/Magnetite inclusions)
igneous
Green glass sphere/marble
Soda-lime glass (primarily SiO2, Na2O, CaO)
Man-made object (Simulant)
Quartzite (Iron-stained)
Quartzite (mostly SiO2 with Fe2O3 impurities)
metamorphic
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
sedimentary
Mica Schist (with Muscovite mica)
Mica Schist (KAl2(AlSi3O10)(OH)2)
metamorphic
Obsidian
Volcanic glass
igneous
Arsenopyrite in Quartz Matrix
Arsenopyrite (FeAsS) with Quartz (SiO2)
Mineral in a Metamorphic/Hydrothermal rock
Ironstone (Limonite/Hematite concretion)
Ferruginous Siltstone / Goethite (FeO(OH))
sedimentary
Obsidian
Volcanic glass
igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous