Ironstone Concretion / Chert Nodules
Iron-rich Sedimentary Concretion (Fe2O3 / SiO2 mix)
Category
Browse sedimentary (imitation) specimens identified by the Rock Identifier community.
Ironstone Concretion / Chert Nodules
Iron-rich Sedimentary Concretion (Fe2O3 / SiO2 mix)
Ironstone (Limonite/Hematite concretion)
Ferruginous Siltstone / Goethite (FeO(OH))
Quartz (Chert / Agate / Chalcedony)
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO2)
Yellow Ocher (Iron-rich Silt/Clay)
Goethite-rich Limonite (FeO(OH)qnH2O)
Orange Calcite
Calcium Carbonate (CaCO3)
Yellow Calcite
Calcium Carbonate (CaCO3)
Yellow Calcite
Calcium Carbonate (CaCO3)
Shale
Shale (fine-grained clastic sedimentary rock)
Rounded brown pebble, likely weathered sandstone or iron-stained quartzite
Probable quartz-rich sandstone (SiO₂-dominated); exact identification requires testing
Shale
Mudrock / Fissile Shale
Sandstone
Clastic sedimentary rock (primarily SiO2)
Banded Jasper (Mookaite / Chert)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Fossil Coral
Tabulate Coral (potentially Favosites or Calapoecia)
Gastropod Steinkern (Internal Mold Fossil)
Gastropoda (Class); Internal mold or 'Steinkern' composed of Calcium Carbonate (CaCO3) or Sedimentary matrix
Weathered sandstone or siltstone
Clastic sedimentary rock, chiefly quartz and feldspar grains cemented by clay, silica, or iron oxides
Shale (or Mudstone)
Clay mineral aggregate / Fine-grained siliciclastic sedimentary rock
Chert (Tan/Yellow variety)
Microcrystalline quartz (SiO2)
Sandstone (Ferruginous)
Arenite with Iron Oxide (Fe2O3) cement
Chert (Common Opal/Chalcedony variety)
Microcrystalline Quartz (SiO2)
Knightia Fossil in Limestone
Knightia eocaena in micritic limestone
Puddingstone (Gowganda)
Gowganda Formation Conglomerate
Agate
SiO2
Fossil Shell
Invertebrate fossil (Mollusca)
Quartz
Silicon Dioxide (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Orange Calcite
Calcium Carbonate (CaCO3)
Pyrite
Iron Sulfide (FeS2)
Limonite Geode (Ironstone Concretion)
Limonite [FeO(OH)·nH2O] with possible Quartz or Calcite interior
Conglomerate
Conglomerate (Sedimentary Rock)
Red sandstone
Quartz-rich sandstone, commonly ferruginous (Fe-oxide stained)
Fossiliferous Limestone with Brachiopod
Phylum Brachiopoda in calcitic matrix
Lepidodendron Fossil in Sandstone
Lepidodendron (Lycophytina, Lepidodendrales)
Pebble (likely Quartz or Chert)
SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.
Chert (Jasper/Opaline variety)
Silicon Dioxide (SiO2)
Weathered limestone
Calcite-rich carbonate rock (mostly CaCO₃)
Fossilized shell fragment
Indeterminate fossil mollusk; likely a silicified or mineral-replaced bivalve/gastropod fragment
Red Jasper
Silicon Dioxide (SiO2) with Iron impurities
Blue Apatite
Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)
Pyrite
Iron Sulfide (FeS2)
Sandstone (Micaceous)
Arenite (composed primarily of SiO2)
Sandstone (Water-worn Pebble)
Clastic Sedimentary Rock (primarily SiO2)