Iron-rich sandstone or weathered ironstone fragment
Ferruginous sandstone; quartz (SiO₂) cemented or stained by iron oxides such as hematite/goethite
sedimentary
Category
Sedimentary (Anthropogenic)
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Glauconitic Sandstone
Glauconitic Sandstone (Quartz with Glauconite)
sedimentary
Fossil Sponge / Horn Coral / Crinoid Stem
Phylum Porifera or Cnidaria fossilized in calcium carbonate / silica
fossil
Sandstone or similar clastic rock
Arenite
sedimentary
Limonite with Trace Fossils
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) in Geode formation
mineral
Fossilized Bone in Matrix
Vertebrata fossil
fossil
Chalcedony
Silicon Dioxide (SiO2)
mineral
Fossil Shell
Gastropoda
fossil
Sandstone or possibly a conglomerate
Arenite (if sandstone)
sedimentary
Fossil shell fragment in sedimentary rock
Indeterminate marine mollusk shell; likely a bivalve or gastropod fossil
fossil
Quartz-veined Sandstone Pebble
Quartzite-veined Arenite
sedimentary
Devil's Toenail
Gryphaea (extinct genus of foam oysters, typically composed of Calcite CaCO3)
sedimentary
Polished red jasper and carnelian-like stones
Jasper: microcrystalline quartz (SiO₂), commonly colored by iron oxides; translucent piece may be carnelian, a chalcedony variety
mineral
Ocean Jasper
Orbicular Jasper (Silicon Dioxide, SiO2)
sedimentary
Coquina / Shelly Sandstone
Calcareous Sandstone / Coquina
sedimentary
Ironstone Pebble
Sedimentary Ironstone (Hematite/Limonite-bearing)
sedimentary
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Shell
Invertebrate fossil (phylum Mollusca)
fossil
Sandstone
Quartz arenite / Clastic sedimentary rock
sedimentary
Sandstone
Sedimentary Clastic Rock (Quartz Arenite)
sedimentary
Sandstone
Sedimentary Clastic Rock (Quartz-rich)
sedimentary
Sandstone (Ferruginous)
Arenite (SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Coal
Bituminous Coal / Carbonaceous Rock
sedimentary
Weathered sandstone pebble
Quartz-rich sandstone; predominantly SiO₂ grains cemented by silica, calcite, or iron oxides
sedimentary
Rounded iron-rich river pebble, likely sandstone or ironstone
Indeterminate ferruginous sandstone/ironstone; exact identification requires closer examination
sedimentary
Likely milky quartz
Quartz (silicon dioxide, SiO₂)
mineral
Clear quartz crystal pendant
Quartz (silicon dioxide, SiO₂)
mineral
Likely bituminous coal
Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed from the image
sedimentary
Banded sandstone
Quartz-rich sandstone (quartz arenite or feldspathic sandstone; exact type cannot be determined from the image)
sedimentary
Sandstone or Siltstone
Arenite or Siltstone
sedimentary
Bivalve Fossil in Sedimentary Matrix
Fossiliferous Mudstone (Class: Bivalvia)
sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
sedimentary
Smooth gray river pebble
Likely fine-grained sandstone or siltstone; exact identification requires a fresh surface and tests
sedimentary
Honey calcite (orange calcite)
Calcite, calcium carbonate (CaCO₃)
mineral
Quartz Geode with Calcite
Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3)
mineral
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
mineral
Red Jasper
Red Jasper (SiO2)
sedimentary
Quartz on Host Rock
Silicon Dioxide (SiO2)
Mineral Specimen
Jasper with Iron Staining
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Jasper
Silicon dioxide (SiO2)
sedimentary