Sandstone (Ferruginous)
Arenite with Iron Oxide staining (Fe2O3)
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.
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Agate Geode
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Sandstone (Ferruginous Concretion)
Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement
sedimentary
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Nodule / Ironstone Concretion
Microcrystalline Quartz (SiO2) with Iron Oxides
sedimentary
Quartz Druzy on Geode Fragment
Silicon Dioxide (SiO2)
mineral
Tumbled brown translucent stone, likely quartz/jasper
Microcrystalline quartz (SiO₂), possibly iron-stained chalcedony or jasper
mineral
Quartz Geode in Sedimentary Matrix
Silicon Dioxide (SiO2) within a limestone/dolostone host
mineral
Vesicular Basalt (Scoria)
Mafic extrusive igneous rock (primarily Plagioclase Feldspar and Pyroxene)
igneous
Hag Stone (Adder Stone / Geode-bearing Pebble)
Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)
sedimentary
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Agate Geode / Nodular Chalcedony
Silicon Dioxide (SiO2) with impurities
mineral
Quartz Druze on Matrix
Silicon Dioxide (SiO2)
mineral
Geode
Crystalline Quartz (SiO2) within a nodule
sedimentary
Mixed river-worn rock and mineral collection
Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble
igneous, sedimentary, metamorphic, mineral
Ironstone Concretion (Limonite/Goethite)
Goethite/Limonite concretion (FeO(OH)·nH2O)
sedimentary
Ironstone Concretion (Moqui Marble type)
Iron oxide concretion (Goethite/Hematite and Sandstone)
sedimentary
Iron Ore / Hematite / Ironstone Nodule
Hematite / Goethite (Fe2O3 / FeO(OH))
sedimentary
Celestine (or Celestite) on Matrix
Celestine (SrSO4)
mineral
Amethyst Geode
Silicon dioxide (SiO2) with iron impurities
mineral
Quartz (likely) or a Quartzite Pebble
Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.
Mineral, specifically a detrital grain
Quartz Geode
Crystalline Silicon Dioxide (SiO2) within a geode structure
mineral
Sandstone (Ferruginous)
Arenite (with iron oxide cement, Fe2O3)
sedimentary
Quartz Druze on Matrix (Geode Fragment)
Quartz (Silicon Dioxide, SiO2)
mineral
Celestite
Celestine (Strontium Sulfate, SrSO4)
mineral
Weathered iron-rich rock, possibly limonite-bearing basalt or ironstone
Undetermined; likely iron oxides/hydroxides (goethite–hematite–limonite) in a silicate host
mineral
Weathered quartz-bearing rock, possibly sandstone or quartzite
Provisional: quartzite (mostly SiO₂); could alternatively be iron-stained quartz sandstone
metamorphic
Unidentified Rock
Unknown
sedimentary
Dyed Blue Agate Slice
Silicon Dioxide (SiO2) - Variety Agate
mineral
Chert (Jasper-rich)
Silicon Dioxide (SiO2)
sedimentary
Sandstone
Arenite (primarily Quartz Arenite)
sedimentary
Ironstone Concretion
Ferruginous Concretion
sedimentary
Septarian Nodule
Septarian Concretion
sedimentary
Agate (Banded Chalcedony)
Cryptocrystalline Silica (SiO2)
mineral
Sandstone (Greywacke)
Arenite / Greywacke Sandstone
sedimentary
Small white mineral fragment
Indeterminate; possibly quartz, calcite, or feldspar
mineral
Septarian Nodule (Dragon Stone) sphere
Septarian concretion (Calcite, Aragonite, and Limestone)
sedimentary
Chert Nodule (with Geode cavity)
Cryptocrystalline Quartz (SiO2)
sedimentary
Agate (Carnelian / Chalcedony)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Quartz (Druzy)
Silicon Dioxide (SiO2)
mineral
Fossil Coral
Tabulate Coral (potentially Favosites or Calapoecia)
fossil
Ironstone Concretion (Limonite/Goethite)
Ironstone (composed primarily of Goethite FeO(OH) and Limonite)
sedimentary