sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness: 3 on Mohs scale, Color: White, gray, tan, or yellowish, Luster: Earthy to dull, Crystal structure: Trigonal (as calcite), Cleavage: Perfect rhombohedral
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Physical properties
Hardness: 3 on Mohs scale, Color: White, gray, tan, or yellowish, Luster: Earthy to dull, Crystal structure: Trigonal (as calcite), Cleavage: Perfect rhombohedral
Formation & geological history
Formed by the accumulation of skeletal fragments of marine organisms such as coral, algal, and foraminifera in shallow marine environments over millions of years.
Uses & applications
Used extensively in construction (as building blocks, crushed stone for road base, and raw material for cement), agriculture (soil conditioning), and metallurgy.
Geological facts
Limestone often contains fossils of ancient marine life and makes up about 10% of the total volume of all sedimentary rocks on Earth.
Field identification & locations
Easily identified by its reaction with weak hydrochloric acid (effervescence/fizzing due to carbon dioxide release). Found globally in sedimentary basins and ancient sea beds.
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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
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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)
sedimentary