sedimentary
Limestone
Calcium carbonate (CaCO3)
AI-generated identification · may be incorrectHardness of 3 on the Mohs scale, typically gray, white, or tan with a dull to earthy luster, and massive or fine-grained crystal structure.
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Physical properties
Hardness of 3 on the Mohs scale, typically gray, white, or tan with a dull to earthy luster, and massive or fine-grained crystal structure.
Formation & geological history
Formed from the accumulation of skeletal fragments of marine organisms or chemical precipitation in shallow marine environments over millions of years.
Uses & applications
Widely used in construction as building stone, aggregate in concrete, raw material for cement, and in agricultural soil treatment.
Geological facts
Limestone often contains well-preserved fossils and forms dramatic landscapes like caves and sinkholes via chemical weathering.
Field identification & locations
Easily identified by its characteristic fizz when tested with 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