sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectLimestone has a Mohs hardness of 3, ranges in color from white to gray or tan, and exhibits a dull to earthy luster with no distinct crystal structure visible to the naked eye.
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Physical properties
Limestone has a Mohs hardness of 3, ranges in color from white to gray or tan, and exhibits a dull to earthy luster with no distinct crystal structure visible to the naked eye.
Formation & geological history
It forms primarily in shallow marine environments through the accumulation of shell, coral, algal, and fecal debris, or via chemical precipitation of calcium carbonate.
Uses & applications
Commonly used in the manufacture of cement, as crushed stone for road base, in agriculture to neutralize soil acidity, and as a dimension stone in construction.
Geological facts
Limestone frequently contains well-preserved fossils of ancient marine organisms and is famously used to build the Great Pyramids of Giza.
Field identification & locations
It is easily identified in the field by its effervescence (fizzing) when a drop of dilute hydrochloric acid is applied.
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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
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Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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