Limestone
Calcium Carbonate (CaCO3)
sedimentary
Category
Not A Rock (Man Made Origin)
Browse not a rock (man made origin) specimens identified by the Rock Identifier community.
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Fossilized cylindrical shell or bone fragment
Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone
fossil
Gossanous Sandstone (likely Terrestrial)
Arenite with Iron-Oxide inclusions
sedimentary
Rounded dark river pebble, likely basalt
Basalt; fine-grained mafic volcanic rock, typically plagioclase + pyroxene ± olivine
igneous
Glauconitic Sandstone
Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
sedimentary
Sedimentary Breccia
Clastic Breccia (CaCO3/SiO2 matrix)
sedimentary
River Pebbles (Mixed Lithology)
Conglomerate clasts (Silica-rich and Metamorphic assemblages)
sedimentary
Blue Sapphire
Corundum (Al2O3 with iron and titanium trace elements)
mineral
Granite
Phaneritic plutonic igneous rock (SiO2-rich)
igneous
Lapis Lazuli (Low Grade)
Lazurite-rich metamorphic rock ((Na,Ca)8(AlSiO4)6(SO4,S,Cl,OH)2)
metamorphic
Weathered iron-stained quartzite or sandstone cobble
Quartzite (quartz-rich rock), possibly ferruginous sandstone
metamorphic
Small dark metallic-looking rock fragment
Undetermined; possibly iron oxide-rich material or a metallic mineral
mineral
Basalt pebble
Basalt (Mafic Extrusive Igneous Rock)
igneous
Bauxite
Bauxite (Mixture of Hydrous Aluminum Oxides)
sedimentary
Sandstone (Quartzite-rich)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Quartz (Grain)
Silicon Dioxide (SiO2)
mineral
Diamond Druzy (Crystalline Diamond)
Carbon (C)
mineral
Banded Rock (likely Quartz-rich)
Uncertain, likely a Metamorphic Rock (e.g., Gneiss or Schist) with prominent Quartz and other minerals
Mineral
Fossil Coral
Anthozoa (Scleractinia)
fossil
Gneiss
Gneiss
metamorphic
Red Coral
Corallium rubrum
mineral
Rough Emerald in Matrix
Beryl (Be3Al2Si6O18) with trace Chromium/Vanadium
mineral
Basalt
Mafic Igneous Rock (composed primarily of pyroxene and calcium-rich plagioclase)
igneous
Granite
Granite (Felsic Plutonic Rock)
igneous
Grey Chalcedony
Silicon Dioxide (SiO2)
mineral
Gastropod Fossil (Steinkern)
Class Gastropoda (internal mold)
fossil
Pumice
Pumice (Vitreous volcanic rock)
igneous
Lava Rock (Dyed)
Basalt / Volcanic scoria
igneous
Granite
Phaneritic plutonic rock (dominated by Quartz and Feldspar)
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Lapis Lazuli
Lapis lazuli (Complex silicate rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)
metamorphic
Man-made Glass (Tumbled/Shaped)
Amorphous Silicon Dioxide (SiO2) with metal oxide colorants
Mineraloid (synthetic)
Man-made Crystal (Lead Glass)
Lead oxide-doped Silica Glass (approx. SiO2 + PbO)
Mineraloid/Synthetic Material
Man-made Dyed Aura Quartz
Silicon Dioxide (SiO2) with metallic coating/dye
mineral
Pink Aragonite
CaCO3
mineral
Small dark mineral/rock fragment
Indeterminate; possibly magnetite-bearing basalt or iron-rich slag
mineral
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Scoria
Scoria (Vesicular Basaltic Rock)
igneous
Opalite
Man-made synthetic glass with opalescent effects (SiO2 + metal oxides)
mineraloid
Milky quartz-bearing rock, likely quartzite or silicified limestone
Quartz (SiO₂), possibly in a quartzite or chalcedony-rich matrix
metamorphic
Sandstone (Yellow/Tan)
Clastic sedimentary rock (primarily SiO2 with iron oxide staining)
sedimentary
Emerald
Beryl (Be3Al2(SiO3)6) with Chromium and/or Vanadium impurities
gemstone