Opal (in Jewelry Setting)
Hydrated Silicon Dioxide (SiO2·nH2O)
Category
Browse sedimentary (base), then artificial specimens identified by the Rock Identifier community.
Opal (in Jewelry Setting)
Hydrated Silicon Dioxide (SiO2·nH2O)
Limestone
Calcium Carbonate (CaCO3)
Rounded dark river pebble
Likely fine-grained basalt or andesite; exact identification requires a fresh surface or tests
Limestone (Weathered)
Sedimentary carbonate rock, primarily calcium carbonate (CaCO3)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with marine fossils
Sandstone (Ferruginous)
Arenite (Fe-oxide enriched)
Sandstone (with Iron Staining)
Arenite (SiO2 with Fe2O3/FeOOH impurities)
Quartz and Mixed Sedimentary Rocks
Silicon Dioxide (SiO2) mixed with various clastic sedimentary lithologies
Chert (Limestone-based)
Silicon dioxide (SiO2)
Sandstone (with banding)
Arenite (primarily SiO2)
Sandstone (Quartz-rich)
Sandstone (SiO2 dominated)
Ironstone (with possible Hematite/Limonite coating)
Ironstone (Fe-rich sedimentary rock)
Chert Breccia
Brecciated Chert (SiO2)
Coquina
Biogenic Limestone (Calcite, CaCO3)
Sandstone (Greywacke/Siltstone variant)
Clastic Sedimentary Rock (composed primarily of Quartz SiO2 and Feldspar)
Sandstone (with potentially high Feldspar/Arkose content)
Clastic sedimentary rock (SiO2 dominated)
Coquina or Fossiliferous Limestone
Fossiliferous Calcarenite (CaCO3)
River Cobble (Sandstone)
Arenite (primarily SiO2)
Chert (often called Flint or River Stone)
Microcrystalline alpha-quartz (SiO2)
Chert (with Limestone and Iron Oxide staining)
Cryptocrystalline Quartz (SiO2)
Sandstone (Quartzose Sandstone)
Arenite (SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Greywacke (River Slikenside)
Greywacke (Lithic Sandstone)
Greywacke
Lithic wacke (variety of Sandstone)
Granitic Gneiss
Gneiss (Metamorphic rock predominantly containing quartz, K-feldspar, and plagioclase)
Gray Limestone
Calcite-rich Sedimentary Rock (CaCO3)
Sandstone (likely Quartzose Sandstone)
Arenite (composed primarily of SiO2)
Leopard Jasper
Microcrystalline Quartz (SiO2)
K2 Jasper (K2 Granite)
Azurite in Granite (Biotite Granite containing Azurite)
Shale with Quartz Veins
Fissile Sedimentary Rock (SiO2)
Conglomerate
Conglomerate (Sedimentary rock, clastic)
Conglomerate
Conglomerate (clastic sedimentary rock)
Puddingstone
Conglomerate
River Sandstone (Lithic Arenite)
Lithic Sandstone (SiO2 dominated with lithic fragments)
Sandstone (lithic wacke/arenite)
Clastic sedimentary rock (primarily SiO2)
Chert (River Pebble)
Cryptocrystalline Quartz (SiO2)
Sandstone
Arenite (SiO2 based typically)
Quartzite Pebbles with Quartz Veining
SiO2 (Silicon Dioxide with country rock matrix)
Graphite
Graphite (Carbon, C)
Fossil Crab
Decapoda (likely Avitelmessus or Raninidae family)
Chert Pebble
Microcrystalline Quartz (SiO2)