sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness: 3 on the Mohs scale, Color: White, gray, tan, or yellowish, Luster: Earthy to dull, Crystal structure: Trigonal (as calcite)
- Luster
- Earthy to dull, Crystal structure: Trigonal (as calcite)
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Physical properties
Hardness: 3 on the Mohs scale, Color: White, gray, tan, or yellowish, Luster: Earthy to dull, Crystal structure: Trigonal (as calcite)
Formation & geological history
Formed by the accumulation of skeletal fragments of marine organisms like coral, algal, and foraminifera, typically in shallow, warm marine waters over millions of years.
Uses & applications
Used extensively in construction (as building blocks, crushed stone for road base, and a primary component of cement), agriculture (soil conditioning), and metallurgy.
Geological facts
Limestone often contains fossils of ancient sea creatures. Famous structures like the Great Pyramids of Giza were partially built from limestone.
Field identification & locations
Easily identified by its reaction to dilute hydrochloric acid, producing bubbles of carbon dioxide gas. Found worldwide in sedimentary basins.
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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