Agate (Geode/Nodule)
Chalcedony (cryptocrystalline silica, SiO2)
sedimentary
Category
Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)
Browse sedimentary rock (specifically a concretion or possibly a geode) specimens identified by the Rock Identifier community.
Learn about Sedimentary Rock (Specifically A Concretion Or Possibly A Geode) in the encyclopedia
View all →
Geode (Unopened)
Crystalline Quartz or Chalcedony filled Geode (SiO2)
sedimentary
Amethyst (Chevron or Banded variety)
Silicon Dioxide with Iron impurities (SiO2)
mineral
Quartz Geode
Crystalline Silicon Dioxide (SiO2)
mineral
Quartz Geode (Amethyst / Clear Quartz)
Silicon Dioxide (SiO2)
mineral
Geode (Unopened Keokuk Geode)
Silicon Dioxide (SiO2) - Chalcedony / Quartz exterior
mineral
Geode
Quartz nodule / Chalcedony-lined cavity
sedimentary
Ironstone Nodules (Iron Concretion)
Siderite or Hematite Concretion
sedimentary
Boxwork or Septarian Concretion
Septarian nodule / Boxwork weathering
sedimentary
Quartz Geode
Crystalline Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Druzy Quartz on Sandstone
Silicon Dioxide (SiO2) with Quartz crystals
sedimentary
Moqui Marble (Shaman Stone)
Iron Oxide Concretion (Goethite/Hematite shell with Sandstone core)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) in Geode form
sedimentary
Chert (specifically a weathered Chert nodule or fragment)
Chert; Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Quartz Geode Fragment
Silicon Dioxide (SiO2)
sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, Limestone)
sedimentary
Ironstone Concretion
Ironstone (Limonite/Goethite/Hematite mixture)
sedimentary
Ironstone Concretion
Siderite / Hematite-bearing Sedimentary Rock
sedimentary
Sandstone Concretion
Sandstone (Sedimentary rock, mostly SiO2)
sedimentary
Amethyst geode fragment
Quartz, SiO₂; purple color from irradiation-related iron impurities
mineral
Quartz Geode
Crystalline Quartz (SiO2) within a sedimentary or volcanic host
mineral
Iron Concretion
Ferruginous concretion (Fe2O3·nH2O / FeO(OH))
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2) in a concretionary structure
sedimentary
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Weathered gray stone, possibly limestone or concrete-like carbonate rock
Tentatively micritic limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image
sedimentary
Quartz (likely a weathered/tumbled piece)
Quartz (SiO₂)
Mineral
Ironstone Concretion
Ferruginous Concretion (Fe2O3·nH2O)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Geode
Quartz / Chalcedony nodule
sedimentary
Limonite Concretion
Goethite/Limonite (FeO(OH)·nH2O)
sedimentary
Sandstone Concretion
Ferruginous Sandstone Concretion
sedimentary
Limonite Concretion
Limonite (Hydrated iron oxide) FeO(OH)·nH2O
sedimentary
Goethite Concretion
Goethite (FeO(OH))
sedimentary
Limonite Concretion
Limonite (FeO(OH)·nH2O) Pseudomorph
sedimentary
Agate Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Chert Concretion
Sedimentary Cryptocrystalline Quartz (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) in a sedimentary or volcanic host
mineral
Amethyst Lace Agate / Banded Amethyst
Silicon Dioxide (SiO2) with Fe3+ impurities
mineral