sedimentary
Limestone
Calcium carbonate (CaCO3)
AI-generated identification · may be incorrectHardness 3 on the Mohs scale, typically gray, white, or tan in color with an earthy to sub-vitreous luster, and massive or fine-grained crystal structure.
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Physical properties
Hardness 3 on the Mohs scale, typically gray, white, or tan in color with an earthy to sub-vitreous luster, and massive or fine-grained crystal structure.
Formation & geological history
Formed through the accumulation of skeletal fragments from marine organisms like coral, algal, and molluscan remains, typically in shallow, calm, warm marine waters.
Uses & applications
Widely used as a building material, an aggregate for road bases, as a main component of concrete, and in the manufacture of cement and agricultural soil conditioners.
Geological facts
Limestone often contains well-preserved fossils of ancient marine life and can form dramatic karst landscapes featuring caves and sinkholes.
Field identification & locations
Identified easily by its characteristic effervescence when exposed to dilute hydrochloric acid; found globally in sedimentary basins.
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Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary