Banded Siltstone
Siltstone (primarily SiO2 with Al2O3)
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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Fossilized Brachiopod
Brachiopoda (e.g., Rhynchonellida or Spiriferida)
sedimentary
Siltstone Pebble
Siltstone (fine-grained siliciclastic sedimentary rock)
sedimentary
Quartzite Pebble
Quartzite (SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Liesegang Ring Siltstone
Siltstone with iron oxide Liesegang bands
sedimentary
Blue Quartzite (Aventurine)
Quartzite (primarily SiO2) with inclusions of Dumortierite or Magnesio-riebeckite
metamorphic
Calcite
Calcium Carbonate (CaCO3)
mineral
Snowflake Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Snowflake Obsidian
Hydrated Volcanic Glass (primarily SiO2) with Cristobalite inclusions
igneous
Mahogany Obsidian
Obsidian (volcanic glass with Hematite/Magnetite inclusions)
igneous
Mahogany Obsidian
Obsidian with Hematite inclusions (SiO2 + Fe2O3)
igneous
Hardpan Nodule / Ferruginous Sandstone
Ferruginous Sandstone (Fe-cemented sediment)
sedimentary
Ironstone Concretion / Goethite Nodules
Ironstone (composed primarily of Goethite FeO(OH) and Limonite)
sedimentary
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Black Obsidian
Obsidian (Amorphous Silicon Dioxide)
igneous
Snowflake Obsidian
Spherulitic Obsidian (Volcanic Glass with Cristobalite)
igneous
Black Obsidian
Volcanic Glass (SiO2)
igneous
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
Obsidian
Obsidian (principally SiO2)
igneous
Diorite
Diorite (Intermediate intrusive igneous rock)
igneous
Snowflake Obsidian
Spherulitic Obsidian (Amorphous Volcanic Glass with Cristobalite inclusions)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2)
igneous
Obsidian and Phantom Quartz
Volcanic Glass (SiO2 + MgO + Fe3O4) and Crystalline Quartz (SiO2)
igneous and mineral
Concrete fragment with Aggregate
Anthropogenic Concrete with Calcarious and Siliceous Aggregate
sedimentary (anthropogenic/man-made)
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
igneous
Dendritic Siltstone (or Mudstone)
Siltstone with Manganese Oxide dendrites
sedimentary
Pyrite
Pyrite (Iron Disulfide), FeS2
Mineral
Diamond (or Cubic Zirconia simulant)
Carbon (C) - Diamond / Zirconium dioxide (ZrO2) - CZ
mineral
Black Obsidian
Obsidian (Volcanic Glass)
igneous
Apache Tear
Obsidian (Hydrated Volcanic Glass) - SiO2 (with impurities)
igneous
Basalt with Chert/Obsidian blade
Aphanitic Mafic Igneous Rock (Basalt) with Microcrystalline Silica (Chert)
igneous
Snowflake Obsidian
Volcanic Glass (SiO2) with Cristobalite inclusions
igneous
Black Obsidian
Volcanic Glass (SiO2)
igneous
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2)
igneous
Magnetic Sand Grain / Magnetite Pellet
Magnetite (Fe3O4)
mineral
Chinese Writing Stone
Porphyritic Basalt (or Andesite) with Feldspar inclusions
igneous
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
mineral
Scoria (Lava Rock)
Scoria
igneous