sedimentary
Weathered limestone
Limestone, composed chiefly of calcite (CaCO₃)
AI-generated identification · may be incorrectPale beige to tan, rough and fine-grained with irregular fractures; calcite is Mohs 3, typically vitreous to dull, with rhombohedral cleavage. The specimen’s texture suggests limestone, though a photo cannot confirm its composition.
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Physical properties
Pale beige to tan, rough and fine-grained with irregular fractures; calcite is Mohs 3, typically vitreous to dull, with rhombohedral cleavage. The specimen’s texture suggests limestone, though a photo cannot confirm its composition.
Formation & geological history
Forms as carbonate sediment or accumulated shell and skeletal material, later compacted and cemented; limestone ranges from recent deposits to rocks billions of years old.
Uses & applications
Used for cement and lime, building stone, aggregate, and agricultural soil treatment; ordinary rough pieces have little commercial value.
Geological facts
Calcite-rich limestone fizzes when exposed to dilute acid, a useful field test.
Field identification & locations
Common in sedimentary basins worldwide; check for acid reaction and fossils or carbonate grains. Estimated value: about $0–$10 for a common hand specimen.
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