Ferruginous Sandstone (Ironstone)
Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Category
Man Made Material (Simulated Mineral)
Browse man made material (simulated mineral) specimens identified by the Rock Identifier community.
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Marble
Recrystallized Calcite (CaCO3)
metamorphic
Blue opalite (often sold as synthetic opal)
Opalite glass; amorphous hydrated silica if natural opal (SiO₂·nH₂O)
gemstone
Granite (with a dark inclusion or attached fragment)
Granite, mainly quartz, feldspar, and mica; the dark object cannot be identified confidently from the photo.
igneous
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Flint or chert fragment
Microcrystalline quartz (SiO₂), likely flint/chert
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (Yellow/Tan variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert Nodule (Flint)
Chert (Silicon Dioxide, SiO2)
sedimentary
Diamond (in a jewelry setting)
Carbon (C)
mineral
Sandstone (likely Fossiliferous)
Arenite / Fossiliferous Sandstone (SiO2 composition)
sedimentary
Coquina
Bioclastic Limestone (Coquina)
sedimentary
Vesicular basalt (possibly slag-contaminated)
Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals
igneous
Pyrite
Iron Sulfide (FeS2)
mineral
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Blue glassy cabochon, likely blue quartz or synthetic glass
Possibly dyed blue chalcedony/quartz (SiO₂); visual identification is inconclusive
gemstone
Granite
Granite (Felsic Plutonic Rock)
igneous
Green cabochon gemstone, likely aventurine or dyed chalcedony
Indeterminate from image; possible quartz variety (SiO₂), including aventurine quartz or chalcedony
gemstone
Sandstone Pebble
Ferruginous Sandstone (SiO2 with Fe2O3)
sedimentary
Green cabochon gemstone, likely nephrite jade
Nephrite jade—interlocking amphibole fibers, chiefly tremolite-actinolite, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
gemstone
Blue Slag Glass
Amorphous Silica (Byproduct of smelting)
Antropogenic (Man-made)
Porcelain (Kaolin-based)
Alumina silicate ceramic (composed primarily of Kaolinite: Al2Si2O5(OH)4)
metamorphic (man-made/engineered)
Mixed gemstone bead bracelet
Likely rose quartz, amethyst, and possibly rhodonite or lepidolite beads
gemstone
Fossilized Burrow
Trace fossil (Ichnogenus)
fossil
Jasper
Silicon Dioxide (SiO2)
sedimentary
Chert / Green Jasper
Silicon Dioxide (SiO2)
sedimentary
Fossil shark tooth in sediment
Likely fossilized shark tooth, possibly *Carcharhinus* or *Otodus*; exact identification requires the tooth’s full morphology and locality
fossil
Corundum (Ruby variety)
Aluminium oxide (Al2O3)
mineral
Sandstone
Arenite (SiO2, often with CaCO3 or Fe2O3 cement)
sedimentary
Chert (Flint / Jasper)
Silicon Dioxide (SiO2)
sedimentary
Carved quartz (likely rose quartz and green aventurine/quartz)
Quartz, silicon dioxide (SiO₂); green material may be aventurine quartz or serpentine
gemstone
Petrified Wood (Silicified Wood)
Silicified Paleoflora (mainly Quartz, SiO2)
metamorphic
Jasper
Silicon dioxide (SiO2) with impurities
sedimentary
Engineered Quartz (Quartzite look-alike)
Silicon Dioxide (SiO2) composite
mineral-based composite
Coquina
Biogenic Limestone (mostly Calcium Carbonate, CaCO3)
sedimentary
Sandstone
Arenite (siliciclastic sedimentary rock composed mostly of quartz)
sedimentary
Lapis lazuli bead bracelet
Lapis lazuli, chiefly lazurite (Na₃Ca(Si₃Al₃)O₁₂S); commonly with calcite and pyrite
metamorphic
Chert (Black Chert or Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint / Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Flint / Chert
Microcrystalline quartz (SiO2)
sedimentary