Geode (Unopened)
Silica-rich concretion (SiO2)
Category
Browse rock (likely sedimentary) specimens identified by the Rock Identifier community.
Geode (Unopened)
Silica-rich concretion (SiO2)
Quartz Geode (Citrine or Iron-stained Quartz)
Silicon Dioxide (SiO2)
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Limestone (Weathered)
Calcium Carbonate (CaCO3)
Gneiss
High-grade regional metamorphic rock (Foliated)
Black River Stone (likely Basalt or Chert)
Basalt (primarily Plagioclase Feldspar and Pyroxene)
Piddock-bored Mudstone
Lutite (Siltstone or Mudstone) with Pholad borings
Chert / Flint
Chert (Cryptocrystalline Silica, SiO2)
Crinoid Fossil in Limestone
Crinoid (Class Crinoidea) in Fossiliferous Limestone (CaCO3)
Unidentifiable Rock Fragment
Sandstone
Arenite (primarily SiO2)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Limonite (Iron Ore)
Limonite (Hydrous iron(III) oxide-hydroxide mixture, primarily FeO(OH)·nH2O)
Sandstone (Ferruginous)
Arenite with Iron-Oxide Cement
Sandstone (Quartzose Sandstone)
Arenite (SiO2 principal component)
Conglomerate
Conglomerate (clastic sedimentary rock)
Sandstone (Glacial Cobble)
Arenite / Sedimentary Rock (primarily SiO2)
Geode (Unopened)
Siliceous Concretion / Geode
Petrified Wood
Silicified Wood (SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Chert (specifically Gray Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Sandstone (Fossiliferous)
Clastic Sedimentary Rock (primarily SiO2)
Sandstone
Arenite (SiO2 primarily)
Botryoidal Chalcedony (Desert Rose / Agate)
Silicon Dioxide (SiO₂)
Chert (Jasper variation)
Silicon dioxide (SiO2)
Chert / Flint
Microcrystalline Quartz (SiO2)
Chert (often called Flint in dark varieties)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Iron-stained)
Chert (Cryptocrystalline Silica, SiO2)
Sandstone
Arenite (primarily SiO2)
Desert Varnish on Sandstone
Ferromanganese coating on Quartz Arenite
Sandstone (Quartzite-rich)
Clastic Sedimentary Rock (primarily SiO2)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Chipped Glass/Plastic Fragment
Silicon dioxide (SiO2) for glass (amorphous) or various polymer compounds for plastic
Chert Geode or Nodule
Microcrystalline Quartz (SiO2)
Geode (unopened) or Calcareous Nodule
Siliceous or Calcareous Concretion/Nodule
Quartz-veined Sedimentary Rock
Hydrothermally veined Clastic Sedimentary Rock (SiO2 veins in Matrix)
Sandstone
Arenite (primarily SiO2 with various cementing agents)
Sandstone
Arenite (SiO2 principal component)
Brachiopod Fossil
Phylum Brachiopoda (likely Order Rhynchonellida or Spiriferida)
Jasper (likely Kambaba or Crocodile Jasper variety)
Silicon Dioxide (SiO2) with inclusions
Conglomerate
Conglomerate (clastic sedimentary rock)
Feldspathic Granite (likely Syenite or Granite Pegmatite)
Phaneritic Acidic Igneous Rock (KAlSi3O8 dominant with SiO2)