Rounded sandstone or quartz-rich sedimentary pebble
Likely quartz arenite/subarkose; exact identification requires testing
Category
Browse sedimentary (biogenic) specimens identified by the Rock Identifier community.
Rounded sandstone or quartz-rich sedimentary pebble
Likely quartz arenite/subarkose; exact identification requires testing
Banded gneiss
Foliated gneiss, likely quartz–feldspar–biotite or amphibole gneiss
Small pale stone, possibly quartz or limestone
Indeterminate from image; likely quartz (SiO₂) or calcite-rich limestone (CaCO₃)
Chert / Flint Arrowheads
Cryptocrystalline Quartz (SiO2)
Pyrite
Iron Disulfide (FeS2)
Mixed Tumbled Gemstones (Agate, Aventurine, Pyrite, etc.)
Multiple (principally Silicon Dioxide SiO2 and Iron Disulfide FeS2)
Jasper
Silicon dioxide (Microcrystalline Quartz, SiO2)
Sandstone
Sedimentary rock composed mainly of quartz sand
Fossiliferous Sandstone / Fossil Fragment
Fossiliferous Sedimentary Matrix with Indeterminate Fossil Material
Polished brown river pebble (likely chert or fine-grained sandstone)
Indeterminate; probable microcrystalline quartz (chert) or quartz-rich sandstone
Orange Calcite
Calcium Carbonate (CaCO3)
Pyrite
Iron Sulfide (FeS2)
Celestine (Celestite)
Strontium sulfate (SrSO4)
Halite (Rock Salt)
Halite (Sodium Chloride, NaCl)
Fossil oyster shell
Oyster (family Ostreidae), preserved as calcite/aragonite shell
Fossil gastropod shell
Fossilized gastropod, likely a small marine snail; exact genus cannot be determined from the image
Quartz-veined Sandstone Pebble
Quartzose Sandstone with Quartz Veinlets
Weathered iron-rich sandstone or ferruginous siltstone
Clastic sedimentary rock, likely quartz-rich sandstone cemented by iron oxides (Fe₂O₃/Fe₃O₄)
Banded Sandstone (River Pebble)
Arenite (SiO2 primarily)
Calcite
Calcium Carbonate (CaCO3)
Quartzite Sandstone / Quartz Sandstone
Quartz Sandstone (SiO2 with minor mineral impurities)
Fossiliferous Sedimentary Rock
Sedimentary Rock with Invertebrate Fossil Imprint
Sandstone Pebble
Sandstone (primarily Quartz, SiO2)
Shale with Trace Fossils
Fissile mudrock (Shale)
Shale
Shale (clastic sedimentary rock)
Sandstone
Arenite
Shale
Shale (Lutite)
Shale
Fissile mudstone (rich in clay minerals and quartz)
Shale
Fissile mudrock (composed primarily of clay minerals and quartz)
Banded Sedimentary Rock
Sedimentary rock with Liesegang banding
Limonite Concretion
Limonite (Hydrated iron(III) oxide-hydroxide) FeO(OH)·nH2O
Weathered quartz-rich sandstone
Quartz arenite to feldspathic sandstone, primarily SiO₂ with minor feldspar, mica, and iron oxides
Chert
Silicon dioxide (SiO2)
Sandstone
Arenite (primarily SiO2)
Shale
Fissile mudrock (composed of clay-sized particles and detrital grains)
Shale
Fissile Mudstone (primarily composed of phyllosilicate minerals like kaolinite, montmorillonite, and illite)
Shale
Clastic sedimentary rock (primarily clay and silt minerals)
Yellow Ocher (Iron-rich Silt/Clay)
Goethite-rich Limonite (FeO(OH)qnH2O)
Orange Calcite
Calcium Carbonate (CaCO3)
Yellow Calcite
Calcium Carbonate (CaCO3)
Quartz (Chert / Agate / Chalcedony)
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO2)