Sandstone with Iron Concretion
Arenite with Limonite/Goethite Concretion
sedimentary
Category
Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)
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White quartz geode nodule
Quartz (SiO₂), likely a quartz-lined geode or vug in a host rock
mineral
Quartz Geode
Silicon Dioxide (SiO2) in Geodic cavity
sedimentary
Iron-rich concretion (probable hematite/limonite nodule)
Goethite–hematite concretion; FeO(OH) and Fe₂O₃, possibly with quartz/clay
sedimentary
Quartz geode
Microcrystalline quartz (SiO₂), commonly with chalcedony and possible calcite inclusions
mineral
Ironstone Concretion
Ironstone (Siderite/Limonite/Goethite)
sedimentary
Sandstone Concretion
Septarian or Carbonate-cemented Sandstone Concretion
sedimentary
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in Geode form
mineral
Fossiliferous limestone
Bioclastic calcarenite; predominantly calcite (CaCO₃)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Limonite Concretion (Ironstone)
Limonite / Goethite (FeO(OH)·nH2O)
sedimentary
Quartz Geode (Druzy Quartz)
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Septarian Nodule (Septarian Dragon Stone)
Septarian Concretion (CaCO3 + Al2Si2O5(OH)4)
sedimentary
Ironstone Nodule
Ferruginous Sandstone / Limonite Concretion
sedimentary
Basalt
Basalt (composition: Plagioclase, Pyroxene, and Olivine)
igneous
Quartz-rich geode or mineralized cavity in host rock
Likely a quartz-bearing geode; the pale crystals may be quartz (SiO₂), but the photo is not detailed enough for a firm identification.
mineral
Concretion (Sandstone)
Carbonate-cemented Sandstone Concretion
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Sandstone Concretion
Moqui Marble / Iron-oxide Concretion (SiO2 with Hematite/Goethite)
sedimentary
Quartz-rich geode or drusy quartz specimen
Quartz, silicon dioxide (SiO₂), likely coating a carbonate or volcanic-rock cavity
mineral
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, Limestone)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Orbicular/porphyritic stone, likely weathered igneous rock
Indeterminate; possibly orbicular granite or a weathered felsic porphyry
igneous
Quartz Geode
Silicon Dioxide (SiO2) within Sedimentary host rock
mineral
Quartz Geode
Quartz (Silicon Dioxide, SiO2) in a Geode
sedimentary
Geode half
Geode (often quartz/chalcedony based)
sedimentary or igneous
Hematite pseudomorph after a fossil or mineralized object (likely iron-oxide concretion)
Hematite, Fe₂O₃, possibly limonite/goethite-bearing
mineral
Sandstone Geode (Unbroken)
Siliciclastic sedimentary rock (primarily Quartz)
sedimentary
Fossilized bone fragment (probable large mammal limb bone)
Mineral-replaced or permineralized bone; exact taxon cannot be determined from the image
fossil
Quartz Geode
Silicon dioxide (SiO2)
sedimentary
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in a Geode
mineral
Iron-rich sandstone concretion
Ferruginous sandstone, cemented chiefly by iron oxides (such as goethite and hematite)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Spherical sandstone concretion
Sandstone concretion, commonly quartz-rich arenite cemented by calcite, silica, or iron oxides
sedimentary
Geode (Unopened)
SiO2 (Quartz-filled Sedimentary Nodule)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Basalt
Extrusive mafic igneous rock
igneous
Basalt with Epidote Veins
Mafic Igneous Rock (Basalt)
igneous
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral