sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness of 3 on the Mohs scale, typically white, gray, or tan in color, with a dull to earthy luster and fine-grained crystal structure.
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Physical properties
Hardness of 3 on the Mohs scale, typically white, gray, or tan in color, with a dull to earthy luster and fine-grained crystal structure.
Formation & geological history
Formed through the accumulation of shell, coral, algal, and fecal debris, or by chemical precipitation of calcium carbonate from water over millions of years.
Uses & applications
Widely used in construction as building stone, a primary component of Portland cement, and in agriculture to neutralize acidic soils.
Geological facts
Limestone frequently contains well-preserved fossils of ancient marine organisms and makes up about 10% of the total volume of all sedimentary rocks on Earth.
Field identification & locations
Easily identified by its characteristic effervescence when exposed to dilute hydrochloric acid; found globally in marine sedimentary basins.
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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
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary