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 a 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 a fine-grained crystal structure.
Formation & geological history
Formed through the accumulation and compaction of organic remains like shells and coral, or chemical precipitation in marine environments over millions of years.
Uses & applications
Widely used in the manufacturing of cement, as a crushed stone base in construction, and in agriculture for soil neutralization.
Geological facts
Limestone frequently contains well-preserved fossils and forms dramatic landscapes featuring caves and sinkholes due to its solubility in acidic water.
Field identification & locations
Easily identified in the field by its effervescence when exposed to dilute hydrochloric acid; found globally in regions with ancient shallow marine histories.
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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