Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
igneous
Category
Mineral Like Byproduct (Technogenic)
Browse mineral like byproduct (technogenic) specimens identified by the Rock Identifier community.
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Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock with secondary mineral fillings)
igneous
Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
mineral
Chrysocolla on Matrix
Hydrated copper silicates ((Cu,Al)2H2Si2O5(OH)4·nH2O)
mineral
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, and Limestone)
sedimentary
Chert (Chalcedony/Agate)
Microcrystalline Quartz (SiO2)
sedimentary
Milky Quartz with Iron Oxide
Quartz (Silicon Dioxide, SiO2) with Limonite/Goethite staining
mineral
Lepidolite
Lepidolite - K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
mineral
Orange Quartzite / Quartz
Silicon Dioxide (SiO2) with iron oxide inclusions
metamorphic
Bismuth Crystal
Bismuth (Bi)
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Arsenopyrite in Quartz Matrix
Arsenopyrite (FeAsS) with Quartz (SiO2)
mineral
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals like Antigorite, Lizardite, and Chrysotile)
metamorphic
Red Sandstone
Arenite (SiO2 with Fe2O3)
sedimentary
Red Sandstone
Ferruginous Sandstone (SiO2 + Fe2O3)
sedimentary
Fluorite
Calcium Fluoride (CaF2)
mineral
Sandstone (likely Arkosic)
Clastic Sedimentary Rock
sedimentary
Sandstone (likely Arkosic or Quartzose)
Sandstone (SiO2 dominated)
sedimentary
Green Aventurine
Quartz (Silicon Dioxide, SiO2) with fuchsite inclusions
mineral
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Biotite / Black Mica
Biotite K(Mg,Fe)3AlSi3O10(F,OH)2
mineral
Rough Blue Sapphire
Corundum (Al2O3)
mineral
Fluorite (left), Sodalite (middle), Dumortierite/Tumbled Quartzite (right)
Calcium Fluoride (CaF2), Sodium Aluminum Silicate Chloride (Na8(Al6Si6O24)Cl2), Aluminum Borosilicate (Al7(BO3)(SiO4)3O3)
mineral
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Blue Apatite
Fluorapatite / Apatite Group (Ca5(PO4)3(F,Cl,OH))
mineral
Quartz Geode
Crystalline Silver Oxide (SiO2) in Calcareous Host
mineral
Botryoidal Chalcedony (likely Desert Rose/Agatized Geode Crust)
Silicon Dioxide (SiO2)
mineral
Orthoclase Feldspar
Orthoclase (KAlSi3O8)
mineral
Amethyst Geode
Amethyst (Silicon Dioxide, SiO2 with iron impurities)
mineral
Chalcedony with Druzy Quartz
Silicon Dioxide (SiO2)
mineral
Agate
Silicon dioxide (SiO2)
mineral
Turtle Stone / Septarian Nodule (Water-worn)
Septarian Concretion
sedimentary
Fossilized Coral
Cnidaria fossil / Calcite-replaced coral
fossil
Conglomerate
Conglomerate (SiO2, CaCO3 dominant)
sedimentary
Blue Quartz (Aventurine)
Silicon Dioxide (SiO2) with Crocidolite or Magnesio-riebeckite inclusions
metamorphic
Granite
Granite
igneous
Granitic Pegmatite
Granitic Pegmatite (primarily SiO2 with KAlSi3O8)
igneous
Conglomerate
Conglomerate (Clastic sedimentary rock)
sedimentary
Bauxite
Bauxite (Al2O3·2H2O)
sedimentary
Dyed Magnesite (Howlite imitation)
Magnesium carbonate (MgCO3) with dye
mineral
Chalcedony on Matrix
Silicon Dioxide (SiO2)
mineral
Chalcedony (Common Opal or Agate variant)
Silicon Dioxide (SiO₂)
mineral