Opal
Hydrous silicon dioxide (SiO2·nH2O)
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.
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
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)
Mineral (specifically a mineraloid)
Silver (Sterling Silver)
Argentum (Ag) mixed with Copper (Cu); Formula: Ag+Cu
mineral
Green Quartzite (Aventurine-like)
Quartzite (primarily SiO2 with chromium-rich mica or chlorite inclusions)
metamorphic
Smoky Quartz (Chlorite Inclusions)
Silicon Dioxide (SiO2) with trace Aluminum and Natural Irradiation
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Chert (Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Almandine Garnet
Almandine (Fe3Al2(SiO4)3)
mineral
Ruby
Corundum (mineral species), variety: Ruby (Al2O3 with Cr3+ as the chromophore)
Mineral
Botryoidal Chalcedony (Agate/Desert Rose Chalcedony)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
mineral
Blue Quartzite (River Pebble)
Quartzite (primarily SiO2 with Dumortierite or Crocidolite inclusions)
metamorphic
Yellow Agate
Agate (Varietal form of Chalcedony/Quartz, SiO2)
mineral
Schist
Schist (various mineralogical compositions including mica, chlorite, talc, etc.)
Metamorphic
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Aquamarine
Beryl (Be3Al2Si6O18 with iron impurities)
mineral
Jasper (Iron-stained Chalcedony)
SiO2 with Fe2O3 (Iron Oxide) impurities
Sedimentary / Mineral (Silica)
Agate Slices and Clear Quartz Points
Agate (SiO2 Chalcedony) and Clear Quartz (SiO2 Crystalline)
mineral
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Porphyritic Basalt (Peanut Obsidian/Star Galaxy-style)
Porphyritic Basalt (Silica-rich Volcanic Rock)
igneous
Cubic Zirconia (Simulated Diamond)
Zirconium Dioxide (ZrO2)
mineral (synthetic)
Basalt Water-Worn Pebble
Aphanitic Mafic Igneous Rock
igneous
Calcite (Yellow/Orange variety - sometimes called Honey Calcite)
Calcite
Mineral
Mica Schist
Mica Schist (primarily Muscovite or Biotite sheet silicates)
metamorphic
Sandstone (Ferruginous)
Arenite (primarily SiO2 with Fe2O3 inclusions)
sedimentary
Digital Multimeter (Synthetic Object)
Digital Multimeter (DMM)
not a rock
Quartzite pebble
Quartzite (SiO2)
metamorphic
Bituminous Coal
Bituminous coal (Carbonaceous sedimentary rock)
sedimentary
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3/FeO(OH)) inclusions
mineral
Turquoise
Turquoise (CuAl6(PO4)4(OH)8·4H2O)
mineral
Peridot
Olivine ((Mg,Fe)2SiO4)
Mineral
Quartz (milky quartz variety)
Quartz (SiO₂)
Mineral
Veined Pebble (likely a Quartz-Veined Pebble)
Pebble with Mineral Vein (e.g., Quartz Vein in a Chert/Mudstone Pebble)
Sedimentary Rock (possibly conglomerate or breccia with a quartz vein)
Pink Quartzite
Quartzite (primarily SiO2)
metamorphic
Diamond
Cubic Carbon (C)
mineral
Crushed Stone (Basalt/Gabbro)
Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
igneous
Asphalt (Road Aggregate)
Bituminous Conglomerate / Asphalt Concrete
Anthropogenic (Man-made)
Banded Agate (Brazilian Agate Slice)
Chalcedony (Silicon Dioxide / SiO2)
Mineral
Transit Token (RTD Denver)
Nickel-plated brass or bronze alloy (Cu-Sn-Zn-Ni)
not a rock or mineral (anthropogenic material)
Olivine (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Orange Quartzite (River Pebble)
Quartzite (primarily SiO2)
metamorphic
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary