Obsidian and Phantom Quartz
Volcanic Glass (SiO2 + MgO + Fe3O4) and Crystalline Quartz (SiO2)
Category
Browse organic gemstone (not a rock or mineral) specimens identified by the Rock Identifier community.
Obsidian and Phantom Quartz
Volcanic Glass (SiO2 + MgO + Fe3O4) and Crystalline Quartz (SiO2)
Moonstone (Feldspar variety)
Orthoclase Feldspar (KAlSi3O8)
Conglomerate
Conglomerate rock
Quartz
Quartz (SiO₂)
Amethyst
SiO2 (Silicon Dioxide with Iron impurities)
Fossil Shark Tooth (Otodus obliquus)
Otodus obliquus; hydroxyapatite (mineralized form Ca5(PO4)3(OH))
Sandstone (Ferruginous)
Sandstone (Clastic sedimentary rock, predominantly SiO2 with Fe2O3 cement)
Jasper (Iron-stained Chert)
Silicon Dioxide (SiO2) with impurities of Hematite or Goethite
Granular Sandstone
Arenite (variable composition, primarily SiO2)
Turquoise
Turquoise (CuAl6(PO4)4(OH)8·4H2O)
Quartz with Iron Staining
Silicon Dioxide (SiO2) with Ferruginous Oxides
Sandstone
Arenite (composed primarily of SiO2)
Serpentinite
Serpentinite (a rock composed predominantly of serpentine group minerals)
Orthoclase Feldspar
Potassium Feldspar (KAlSi3O8)
Chert (Jasper variety)
Cryptocrystalline quartz (SiO2)
Boxwork Siderite or Sepatarian Nodule Weathering
Siderite (FeCO3) with secondary mineralization or Boxwork Geode fragment
Zoisite with Ruby
Anyolite (Ca2Al3(SiO4)3(OH) with Al2O3:Cr)
Sandstone
Arenite (composed primarily of SiO2)
Rhodonite
Rhodonite (Manganese Iron Magnesium Calcium Silicate - (Mn,Fe,Mg,Ca)SiO3)
Quartz (specifically Rose or Smoky tinted Quartz)
Silicon Dioxide (SiO2)
Sandstone
Arenite (SiO2 primarily)
Asphalt Concrete
Bituminous conglomerate
Sandstone (Quartzose)
Arenite (primarily SiO2)
Sandstone
Arenite (SiO2 primarily)
Agate
Silicon dioxide (SiO2) - variety Chalcedony
Sandstone
Arenite (primarily SiO2)
Sandstone
Arenite (SiO2 based)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Sandstone (Fossiliferous)
Clastic Sedimentary Rock (primarily SiO2)
Sandstone
Arenite (composed primarily of SiO2)
Amethyst
Silicon Dioxide with trace Iron (SiO2)
Travertine (Tufa)
Calcium Carbonate (CaCO3)
Quartz Druze on Matrix
Silicon Dioxide (SiO2)
Porphyry (likely Porphyritic Andesite or Basalt)
Porphyritic Igneous Rock
Sandstone (likely Graywacke or Lithic Sandstone)
Clastic Sedimentary Rock
Iolite (Cordierite)
Cordierite (Magnesium iron aluminum cyclosilicate), Mg2Al4Si5O18
Gabbro
Gabbro (Mafic Plutonic Rock)
Labradorite
(Ca, Na)(Al, Si)4O8
Quartz (likely a macrocrystalline variety like milky quartz or smoky quartz, given the appearance in the image)
Quartz (SiO₂ - Silicon Dioxide)
Pearl
Biogenic CaCO3 (Aragonite)
Lapis Lazuli
Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2
Quartz (Milky/Clear variety)
Silicon Dioxide (SiO2)