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 amorphous or 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 amorphous or fine-grained crystal structure.
Formation & geological history
Formed through the accumulation of organic remains like shells and coral or chemical precipitation in shallow marine environments over millions of years.
Uses & applications
Widely used in the construction industry for crushed stone in road base, manufacturing cement, and as a soil conditioner in agriculture.
Geological facts
Limestone frequently contains well-preserved fossils and dissolves slowly in acidic water, creating dramatic cave systems and karst topography worldwide.
Field identification & locations
Easily identified by its characteristic fizz when exposed to dilute hydrochloric acid; common globally in sedimentary rock layers.
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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)
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Sandstone
Arenite
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Shale
Shale (clastic sedimentary rock)
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Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary