sedimentary
Limestone
Calcium carbonate rock (CaCO3)
AI-generated identification · may be incorrectHardness 3 on the Mohs scale, colors range from white to gray and tan, dull to earthy luster, cryptocrystalline structure with no significant cleavage.
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Physical properties
Hardness 3 on the Mohs scale, colors range from white to gray and tan, dull to earthy luster, cryptocrystalline structure with no significant cleavage.
Formation & geological history
Formed by the accumulation of organic skeletal fragments like coral and shell, or chemical precipitation in shallow marine environments over millions of years.
Uses & applications
Widely used in construction as building stone, crushed stone for road base, production of cement, and agricultural soil conditioning.
Geological facts
Limestone frequently contains well-preserved fossils and dissolves slowly in acidic water, creating extensive cave systems and karst topography.
Field identification & locations
Easily identified by its characteristic effervescence when cold dilute hydrochloric acid is applied; commonly found worldwide 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