Smoky Quartz on Feldspar (Granite Pegmatite)
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)
Category
Browse sedimentary rock (specifically a clastic sedimentary rock formed into a cobble) specimens identified by the Rock Identifier community.
Smoky Quartz on Feldspar (Granite Pegmatite)
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)
Sandstone (Ferruginous)
Arenite (Fe2O3 stained)
Stromatolite
Stromatolite (Cyanobacteria-formed Organo-sedimentary structure)
Limestone
Calcite (CaCO3)
Pink Granite
Granite (Phaneritic igneous rock)
Basalt (River Pebble)
Mafic volcanic rock (primarily Plagioclase feldspar and Pyroxene)
Granite (Phaneritic Igneous Rock)
Granite
Quartzite (River Cobble)
Quartzite (predominantly SiO2)
Unakite
Unakite (Episyenite composition: Feldspar, Epidote, and Quartz)
Quartzite
Quartzite (primarily SiO2)
Amethyst
SiO2 (Silicon Dioxide with Iron impurities and natural radiation influence)
Milky Quartz
Silicon Dioxide (SiO2)
Quartzite
Quartzite (SiO2)
Crushed Limestone (Gravel)
Calcium Carbonate (CaCO3)
Druzy Quartz Geode (Oco or Moroccan variety)
Silicon Dioxide (SiO2)
Travertine
Terrestrial Sedimentary Rock (Calcium Carbonate, CaCO3)
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
Limestone
Calcium Carbonate (CaCO3)
Red Quartzite Slipper Stone
Quartzite (SiO2)
Chert (and Limestone)
Silicon Dioxide (SiO2)
Limestone
Calcium Carbonate (CaCO3)
River Rocks (Black)
Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts
Limestone
Calcium Carbonate (CaCO3)
Limestone (Brecciated/Recrystallized)
Calcium Carbonate (CaCO3)
Sandstone (with possibly iron oxides and other minerals)
Sandstone
Mica (Biotite and Muscovite) in Matrix
Potassium aluminum silicate with iron/magnesium (KAl2(AlSi3O10)(F,OH)2 / K(Mg,Fe)3AlSi3O10(F,OH)2)
Limestone (Grey and White specimens)
Calcium Carbonate (CaCO3)
Basalt (Polished River Stone)
Basalt (Extrusive Mafic Volcanic Rock)
Cockle Shell (Fossil or Recent)
Class Bivalvia, Family Cardiidae (e.g., Cerastoderma edule for common cockle)
Limestone
Sedimentary Calcium Carbonate (CaCO3)
Chert (Agatized)
Silicon dioxide (SiO2)
Hematite Nodules (Moqui Marbles style)
Iron Oxide (Fe2O3)
Carnelian (Chalcedony)
Silicon Dioxide (SiO2)
Carnelian
Carnelian (Silicon Dioxide - SiO2)
Geode (Unopened)
Siliceous Concretion / Geode
Red Jasper (possibly Red Coral or dyed Howlite)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
River/Stream Pebble
Clast / Detrital Grain / Rounded Sedimentary Particle (Compositionally variable, commonly Quartz, Feldspar, Chert, or other resistant rock fragments)
Pink Granite
Phaneritic Felsic Igneous Rock (Granite)
Hypersthene
Hypersthene ((Mg,Fe)SiO₃)
Flower Agate (Plume Agate)
Chalcedony (Silicon Dioxide) with Spherulitic Inclusions - SiO2
Andesite Porphyry (River Cobble)
Porphyritic Andesite
Shale
Fissile Mudrock (Clay-rich Sedimentary Rock)