Concretion (Sandstone)
Carbonate-cemented Sandstone Concretion
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 →
Pebble or Cobble (likely composed of sandstone or conglomerate)
Clastic Sedimentary Rock (specific name like sandstone, conglomerate, or breccia would require microscopic analysis of clast size and angularity)
Sedimentary Rock (possibly a conglomerate or coarse-grained sandstone)
Septarian Nodule (Yellow Jasper variety)
Septarian Nodule (comprising Calcite, Aragonite, and Limestone/Bentonite)
sedimentary
Ironstone Concretion
Ironstone (Siderite/Limonite/Goethite)
sedimentary
Sandstone Concretion
Septarian or Carbonate-cemented Sandstone Concretion
sedimentary
Sandstone Geode (Unbroken)
Siliciclastic sedimentary rock (primarily Quartz)
sedimentary
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in Geode form
mineral
Quartz Geode
Silicon dioxide (SiO2)
sedimentary
Limonite Concretion (Ironstone)
Limonite / Goethite (FeO(OH)·nH2O)
sedimentary
Ironstone (Limonite/Hematite)
Ferruginous sedimentary rock (Fe2O3·nH2O / Fe2O3)
sedimentary
Basalt
Basalt (composition: Plagioclase, Pyroxene, and Olivine)
igneous
Shale (possibly)
Shale (fine-grained clastic sedimentary rock)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Ironstone Nodule
Ferruginous Sandstone / Limonite Concretion
sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, Limestone)
sedimentary
Druzy Quartz Geode (Oco or Moroccan variety)
Silicon Dioxide (SiO2)
mineral
Sandstone with Iron Concretion
Arenite with Limonite/Goethite Concretion
sedimentary
Quartz Crystal (specifically a Double-Terminated variety)
Silicon Dioxide (SiO2) - Low Quartz
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Sandstone (specifically Cross-bedded Sandstone)
Arenite (composed primarily of SiO2)
sedimentary
Sandstone Concretion
Clastic sedimentary rock (primarily Silica, SiO2, or Calcium Carbonate, CaCO3)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Dalmatian Stone
Peralkaline rhyolite
igneous
Sandstone Concretion
Moqui Marble / Iron-oxide Concretion (SiO2 with Hematite/Goethite)
sedimentary
Unidentified dark mineral/rock fragment
Indeterminate; appearance may fit a sulfide-bearing rock or iron-rich mineral
mineral
Quartz Geode
Quartz (Silicon Dioxide - SiO2) within a Chalcedony and Limonite shell
sedimentary
Gneiss (specifically a weathered or stream-worn specimen)
Gneiss (Foliated Metamorphic Rock)
metamorphic
Quartz Geode
Silicon Dioxide (SiO2) within Sedimentary host rock
mineral
Geode half
Geode (often quartz/chalcedony based)
sedimentary or igneous
Chalcedony or Chert/Jasper with secondary mineral staining
SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.
Mineral, potentially a rock with chalcedony/jasper.
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in a Geode
mineral
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Granite Cobble
Phaneritic Felsic Igneous Rock
igneous
Geode with Quartz Crystal Cavity
Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix
sedimentary
Quartz (likely Milky Quartz)
Quartz (SiO₂ - Silicon Dioxide)
Mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Sandstone (with Iron Siderite Concretion)
Arenite with Ironstone Concretion (FeCO3)
sedimentary
Fossil Coral
Coral Limestone (a type of biogenic sedimentary rock)
Sedimentary
Basalt
Extrusive mafic igneous rock
igneous