Iron-stained Quartz
Silicon Dioxide (SiO2) with Limonite/Hematite inclusions
mineral
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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Geode (unopened)
Quartz-filled Geode (SiO2)
sedimentary
Ironstone Concretion
Ironstone (Limonite/Goethite Concretion)
sedimentary
Weathered garnet-bearing gneiss
Quartz–feldspar–mica gneiss with almandine garnet, chiefly Fe₃Al₂(SiO₄)₃
metamorphic
Chert / Chalcedony
Silicon Dioxide (SiO2)
sedimentary
Obsidian
Obsidian (Volcanic Glass, SiO2)
igneous
Rough Sodalite
Sodalite, Na8(Al6Si6O24)Cl2
mineral
Sodalite
Na8(Al6Si6O24)Cl2
mineral
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Black Obsidian
Volcanic Glass (felsic)
igneous
Sandstone Concretion
Clastic sedimentary rock (primarily Quartz SiO2)
sedimentary
Obsidian
Volcanic glass (SiO2-rich extrusive igneous rock)
igneous
Sandstone Cobble with Liesegang Rings
Arenite with iron oxide precipitation (SiO2 matrix with Fe2O3 banding)
sedimentary
Ferruginous Quartzite
Quartzite with Hematite/Limonite inclusions (SiO2)
metamorphic
Dumortierite Quartz (Blue Quartz)
Al7(BO3)(SiO4)3O3 / Quarz with Dumortierite inclusions
mineral
Snowflake Obsidian
Obsidian with Cristobalite inclusions
igneous
Blue Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Syenite
Syenite (Phaneritic Igneous Rock)
igneous
Scoria (Lava Rock)
Mafic extrusive volcanic rock (Scientific formula varies based on mineral content: primarily SiO2, MgO, and FeO)
igneous
Sandstone with Ironstone Concretion
Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))
sedimentary
Ironstone Concretion (Limonite/Goethite)
Ironstone (composed primarily of Goethite FeO(OH) and Limonite)
sedimentary
Scoria (Vesicular Basalt)
Scoria (Extrusive Igneous Rock)
igneous
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Obsidian
Volcanic glass
igneous
Snowflake Obsidian
Obsidian with Cristobalite inclusions (SiO2)
igneous
Ironstone Concretion (Limonite/Goethite)
Ironstone (primarily FeO(OH)·nH2O)
sedimentary
Sodalite in Matrix (often called Blue Marble or Sodalite-Syenite)
Sodalite-bearing Syenite / Na8Al6Si6O24Cl2 (Sodalite component)
igneous
Milky Quartz (Stained with Iron)
Silicon Dioxide (SiO2)
mineral
Epidote (or Epidote-rich rock)
Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).
Mineral, often found in metamorphic rocks but also in sedimentary and igneous rocks
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Sandstone Concretion
Clastic Sedimentary Rock (primarily SiO2 with mineral cement)
sedimentary
Ferruginous Sandstone Concretion (Ironstone Phosphorite)
Ferruginous Sandstone (variable Fe-oxide/hydroxide composition)
sedimentary
Ferruginous Quartz (Iron-stained Quartz)
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
mineral
Mixed Mineral Collection
Multi-mineral Assemblage (Quartz, Jasper, Obsidian, Pyrite, etc.)
mineral
Greenstone
Greenschist (primarily composed of chlorite, actinolite, and epidote)
metamorphic
Obsidian
Obsidian (principally SiO2)
igneous
Dioptase
Dioptase (CuSiO3 · H2O)
mineral
Black obsidian (likely)
Volcanic glass; primarily silica-rich rhyolitic composition (SiO₂-rich, noncrystalline)
igneous
Ironstone Concretion (Desert Varnish / Hematite-Goethite Nodule)
Iron oxide / hydroxide deposit (predominantly Fe2O3 and FeO(OH))
sedimentary