Amethyst
Quartz variety; chemical formula: SiO₂ (silicon dioxide) with Fe³⁺ impurities
Category
Browse mineral like (natural glass) specimens identified by the Rock Identifier community.
Amethyst
Quartz variety; chemical formula: SiO₂ (silicon dioxide) with Fe³⁺ impurities
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Bismuth
Bismuth (Bi)
Dyed Agate Slice
Silicon Dioxide (SiO2) - variety of Chalcedony
Citrine Quartz
Crystalline Silicon Dioxide (SiO2) with Ferric Iron impurities
Granite
Phaneritic Felsic Igneous Rock
Chert Concretion (with typical hematite/limonite staining)
Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)
Granite
Granite (consisting mainly of Quartz, Alkali Feldspar, and Plagioclase)
Rough Diamond
Diamond (Native Carbon), C
Mohave Turquoise (Composite/Stabilized)
Hydrated copper aluminium phosphate (CuAl6(PO4)4(OH)8·4H2O) with stabilizing resin and metallic inclusions
Sandstone
Arenite (SiO2 based with various mineral cements)
Red Sandstone
Arenite (with Iron Oxide)
Red Sandstone
Arenite (predominantly SiO2 with Fe2O3 staining)
Sandstone
Arenite (SiO2 based with quartz, feldspar, or lithic fragments)
Sandstone (Ferruginous)
Arenite (with Iron Oxide cement)
Dyed Blue Agate
Silicon Dioxide (SiO2)
Dyed Quartzite
Tumbled Metamorphosed Quartz (SiO2) with artificial pigment
Yellow Ocher (Limonite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
Sandstone (Cross-bedded Drill Core)
Clastic Sedimentary Rock (primarily SiO2)
Basalt
Basalt (principally Plagioclase Feldspar and Pyroxene)
Shale
Shale (composition varies: primarily clay minerals and quartz)
Amethyst Quartz with Matrix
Silicon Dioxide (SiO2)
Shale (or Mudstone)
Siltstone/Argillite (composed mainly of clay and silt-sized particles)
Blue Topaz (specifically London Blue shade)
Topaz - Al2SiO4(F,OH)2
Smoky Quartz and Chalcedony Geode Fragment
Silicon Dioxide (SiO2)
Howlite (Dyed to resemble Turquoise)
Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)
Riverstone Quartzite (Water-worn Siltstone/Quartzite)
Metamorphosed Quartz-rich Arenite (SiO2)
Staurolite (Fairy Cross)
Staurolite (Fe2+2Al9Si4O23(OH))
Amethyst Quartz
Silicon Dioxide (SiO2) with iron impurities
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Obsidian
Obsidian (Volcanic Glass)
Blue Goldstone
Aventurine Glass (Silicon Dioxide infused with Cobalt/Copper)
Lapis Lazuli
Lapis Lazuli (aggregate of Lazurite, Calcite, and Pyrite)
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
Limonite (Iron Ore)
Hydrous ferric oxides (FeO(OH)·nH2O)
Quartzite
Quartzite (SiO2)
Howlite
Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)
Black Onyx
Silicon Dioxide (SiO2) - variety of Chalcedony
Carborundum (Silicon Carbide)
Silicon Carbide (SiC) / Moissanite (natural form)
Dragon Vein Agate (Dyed/Treated)
Agate (SiO2)
Dyed Agate
Agate (Cryptocrystalline Quartz), SiO2
Golden Healer Quartz
Ferruginous Quartz (SiO2 with Fe2O3 inclusions)