Obsidian
Volcanic Glass (SiO2)
igneous
Category
Not A Natural Rock (Man Made Composite)
Browse not a natural rock (man made composite) specimens identified by the Rock Identifier community.
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Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Fossilized Shark Tooth (Eroded)
Carcharodon sp. or Otodus sp. fragment (likely)
fossil
Fossiliferous Limestone (Crinoid stem fossils)
Sedimentary Limestone with Crinoidea ossicles
fossil
Diamond
Carbon (C)
gemstone
Ruby in Zoisite
Anyolite (composite of Corundum Al2O3 and Zoisite Ca2Al3(SiO4)(Si2O7)O(OH))
metamorphic
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Citrine Quartz
Silicon Dioxide (SiO2)
mineral
Amethyst
Silicon Dioxide (SiO2)
mineral
Mystic Topaz
Aluminum silicate fluoride hydroxide with titanium coating (Al2SiO4(F,OH)2)
mineral
Tumbled greenstone, likely nephrite jade
Nephrite jade (interlocking tremolite–actinolite amphibole; Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂)
metamorphic
Green Quartz (Prasiolite or Aventurine)
Silicon Dioxide (SiO2)
mineral
Ametrine
Quartz (Silicon Dioxide, SiO2)
gemstone
Citrine
Silicon Dioxide (SiO2)
mineral
Chalcopyrite (Peacock Ore)
Chalcopyrite (CuFeS2) with Bornite (Cu5FeS4) oxidation
mineral
Smoky Quartz with Iron Inclusions
Silicon Dioxide (SiO2)
mineral
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Dyed Agate
SiO2 (Silicon Dioxide) - Chalcedony variety
Mineral
Smoky quartz crystal/rough fragment
Quartz (SiO₂), likely smoky quartz
mineral
Polished blue agate/geode slice
Chalcedony (microcrystalline quartz, SiO₂), likely dyed blue
mineral
White quartz-rich pebble
Quartz (SiO₂), possibly milky quartz or quartzite
mineral
Chert or flint
Microcrystalline quartz (SiO₂), likely chalcedony-rich chert
sedimentary
Colorless faceted gemstone, likely cubic zirconia
Synthetic cubic zirconia (zirconium dioxide, ZrO₂); identity is visual and not definitive
gemstone
Milky and Smoky Quartz Cobble
Silicon Dioxide (SiO2)
mineral
Milky quartz (massive quartz)
Quartz, silicon dioxide (SiO₂)
mineral
Dyed Quartz Geode
Dyed crystalline quartz (Silicon Dioxide, SiO2)
mineral
Citrine Quartz
Crystalline Silicon Dioxide (SiO2) with iron impurities
mineral
Raw Sapphire (Corundum)
Aluminum oxide (Al2O3)
gemstone
Obsidian (likely blue-sheen or coated obsidian)
Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, noncrystalline)
igneous
Chert (Commonly known as Flint)
Silicon Dioxide (SiO2)
sedimentary
Fossilized Shell in Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Polished green aventurine
Quartzite dominated by quartz (SiO₂), with green fuchsite mica or chlorite inclusions
mineral
Diamond
Diamond (pure Carbon, C)
mineral
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Citrine Quartz
Silicon Dioxide (SiO2) with trace Iron impurities
mineral
Citrine Quartz
Silicon Dioxide (SiO2) with iron impurities
mineral
Quartz (Yellow / Citrine Pebble)
Silicon Dioxide (SiO2)
mineral
Aventurine
Silicon Dioxide (SiO2) with inclusions of Fuchsite
mineral
Marble
Recrystallized Calcite (CaCO3)
metamorphic
Chert (with Limestone matrix)
Silicon dioxide (SiO2)
sedimentary
Likely polished black stone or obsidian
Obsidian (volcanic glass), chiefly SiO₂
igneous
Mahogany Obsidian
Obsidian with Hematite inclusions (SiO2 + Fe2O3)
igneous