Basalt
Basalt (Mafic volcanic rock)
Category
Browse sedimentary rock (specifically a clastic sedimentary rock formed into a cobble) specimens identified by the Rock Identifier community.
Basalt
Basalt (Mafic volcanic rock)
Green Druzy Quartz (Prasiolite)
Silicon Dioxide (SiO2) with inclusions (typically Chlorite or Actinolite)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Basalt with Magnetite
Crystalline Basalt (Primarily Plagioclase and Pyroxene) with Magnetite (Fe3O4)
Sandstone or Quartzite
Arenite (if sedimentary) / Quartzite (if metamorphic)
Polished Basalt
Basalt (Mafic volcanic rock)
Carnelian
Carnelian Chalcedony (SiO2 with Iron Oxide impurities)
Microcrystalline Limestone Pebble
Carbonate sedimentary rock (Calcium Carbonate, CaCO3)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Chert (Jasper/Flint variety)
Microcrystalline silicon dioxide (SiO2)
Bituminous Coal
Bituminous coal (Carbonaceous sedimentary rock)
Yellow Jasper
Silicon Dioxide (SiO2)
Shale with Plant Fossils / Carbonaceous Shale
Laminated Mudrock (Siliciclastic)
Banded Gneiss
Gneiss
Crushed Limestone
Calcite-rich Sedimentary Rock (CaCO3)
Chert (Flint)
Chert (Microcrystalline Quartz, SiO2)
Chert (often called Flint in various colors)
Silicon Dioxide (SiO2)
Carnelian Agate
Silicon Dioxide (SiO2)
Chert (Common Opal/Jasper variety)
Microcrystalline Quartz (SiO2)
Amethyst (Geode/Druzy)
Silicon Dioxide (SiO2) with iron impurities
Green Aventurine
Silicon dioxide (SiO2) with fuchsite inclusions
Breciated Chert
Brecciated Chert (Microcrystalline Quartz, SiO2)
Jasper
Silicon Dioxide (SiO2) with impurities
Chalk / Sedimentary Limestone
Calcium Carbonate (CaCO3) - Biogenic Sedimentary Rock
Chert (Grey-Green Flint)
Microcrystalline silicon dioxide (SiO2)
Quartzite (specifically a river-worn pebble)
Quartzite (primarily SiO2)
Quartzite
Metamorphosed Quartz Sandstone (SiO2)
Slate
Foliated Metamorphic Rock
Clear/White Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Plume Agate
Silicon Dioxide (SiO2)
Glauconitic Sandstone
Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
Clear Quartz
Silicon Dioxide (SiO2)
Banded Gneiss
Gneiss (High-grade metamorphic rock)
Ironstone (Limonitic Concretion)
Limonite (FeO(OH)·nH2O) with Goethite and Hematite inclusions
Limestone
Calcium Carbonate (CaCO3)
Gneiss
Gneiss
Pink Granite (Crystalline Granite)
Igneous Intrusive Rock (Felsic Plutonic)
Slate
Slate (Metamorphic Rock)
Oolitic Limestone (Egg Stone)
Oolite (Chemical sedimentary rock, primarily CaCO3)
Quartz (Druzy or Geode fragment)
Silicon Dioxide (SiO2)