Limestone
Calcium Carbonate (CaCO3)
sedimentary
Category
Sedimentary (Base), Then Artificial
Browse sedimentary (base), then artificial specimens identified by the Rock Identifier community.
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Ferruginous Sandstone (with possible Epidote/Chlorite coloring)
Sandstone (SiO2 dominated with Fe2O3 staining)
sedimentary
Limestone (Micrite/Chalky variety)
Calcium Carbonate (CaCO3)
sedimentary
Limestone (specifically Dolomitic/Crystalline Limestone)
Sedimentary Carbonate Rock (CaCO3 / CaMg(CO3)2)
sedimentary
Gneiss
Gneiss (SiO2-rich metamorphic rock)
metamorphic
River Stone (Quartzite/Siltstone mixture)
Silicon Dioxide (SiO2) based metamorphosed sandstone
metamorphic or sedimentary
Jasper / Quartz Pebble
Silicon Dioxide (SiO2) with microcrystalline impurities
sedimentary
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Smooth gray river pebble
Likely fine-grained sandstone or siltstone; exact identification requires a fresh surface and tests
sedimentary
Breccia
Breccia - Clastic sedimentary rock
sedimentary
Banded Onyx (Mexican Onyx / Travertine)
Calcite (CaCO3) - Banded Travertine
sedimentary
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Ironstone (Limonite/Hematite)
Ferruginous Sedimentary Rock (composed largely of Fe2O3 and FeO(OH)·nH2O)
sedimentary
Ferruginous Quartz
Ferruginous Quartz (Silicon Dioxide + Iron Oxide, SiO2 + Fe2O3)
mineral
Gneissic Granite
Granite Gneiss
metamorphic
River Rock
Mixed lithology clast
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Sandstone Pebble
Arenite (SiO2 with minor mineral cements)
sedimentary
Chalcedony (Common Agate pebble)
Silicon Dioxide (SiO2)
mineral
Sandstone (likely Greywacke or Siltstone variety)
Arenite / Siltstone (primarily SiO2)
sedimentary
Sandstone (Weathered Pebble)
Arenite (composed primarily of SiO2)
sedimentary
Sandstone
Arenite (SiO2 based with mineral cement)
sedimentary
Gneiss
Gneiss
metamorphic
Chert
Microcrystalline silica (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Graphite
Carbon (C)
mineral
Banded Gneiss
Gneiss (Felsic to Mafic Metamorphic Rock)
metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Chert (Arrowhead/Projectile Point)
Microcrystalline Quartz (SiO2)
sedimentary
Dragon Blood Jasper
Epidote with Red Piedmontite (Chalcedony/Quartz variant)
sedimentary
Limestone (specifically a Crushed Aggregate fragment)
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (with Iron Staining)
Arenite (Silicon Dioxide, SiO2, often with iron oxides like Limonite)
sedimentary
Chert (Iron-stained)
Chert (Cryptocrystalline Silica, SiO2)
sedimentary
Siltstone
Siltstone (primarily SiO2 with Al2O3)
sedimentary
Chert (likely flint)
Microcrystalline quartz, SiO₂
sedimentary
Granite Gneiss
Gneiss (containing quartz, alkali feldspar, plagioclase, biotite/amphibole)
metamorphic
Gneiss
Gneiss (Metamorphic rock composed primarily of quartz, feldspar, and mica)
metamorphic
Chert (River Siltstone/Quartzite)
Sedimentary Cryptocrystalline Quartz (SiO2)
sedimentary
Coquina or Fossiliferous Sandstone
Fossiliferous Calcarenite (CaCO3 with SiO2 inclusions)
sedimentary
Limestone (Fossiliferous)
Calcium Carbonate (CaCO3)
sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary