sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness 3 on the Mohs scale, typically white, gray, or buff in color, with a dull to earthy luster and fine-grained crystal structure.
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Physical properties
Hardness 3 on the Mohs scale, typically white, gray, or buff in color, with a dull to earthy luster and fine-grained crystal structure.
Formation & geological history
Formed through the accumulation and compaction of organic remains like shell and coral debris in marine environments, often dating from the Paleozoic to Cenozoic eras.
Uses & applications
Widely used in construction for road base, aggregate in concrete, production of cement, and as a soil conditioner in agriculture.
Geological facts
Limestone frequently contains well-preserved fossils of ancient marine organisms and can dissolve in acidic groundwater to form spectacular cave systems.
Field identification & locations
Easily identified by its characteristic fizz when exposed to dilute hydrochloric acid; found globally in regions with ancient shallow seas.
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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