sedimentary
Limestone Boulder
Sedimentary Rock (Calcium Carbonate, CaCO3)
Hardness of 3 on the Mohs scale; color ranges from white, tan, gray to light brown; dull to earthy luster; fine-grained to crystalline crystal structure; excellent cleavage in three directions (rhombohedral); specific gravity around 2.7.
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Physical properties
Hardness of 3 on the Mohs scale; color ranges from white, tan, gray to light brown; dull to earthy luster; fine-grained to crystalline crystal structure; excellent cleavage in three directions (rhombohedral); specific gravity around 2.7.
Formation & geological history
Formed through the accumulation and compaction of organic remains such as shells, coral, and algal debris, or through the chemical precipitation of calcium carbonate from water, typically in shallow marine environments over millions of years.
Uses & applications
Extensively used in construction, as a building material, in the manufacture of cement and lime, road base, aggregate, and in agriculture to neutralize acidic soils.
Geological facts
Limestone often contains well-preserved fossils of ancient marine organisms and is famously known for forming dramatic cave systems and karst landscapes through chemical weathering by acidic groundwater.
Field identification & locations
Easily identified in the field by its characteristic reaction to dilute hydrochloric acid (it fizzes vigorously due to the release of carbon dioxide). Commonly found worldwide in sedimentary basins and exposed escarpments.
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