sedimentary
Limestone
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness: 3 (Mohs scale), Color: tan-yellowish, Luster: dull to earthy, Crystal Structure: Trigonal (often microscopic), Cleavage: Rhombohedral (not visible in grain), Specific Gravity: 2.5-2.7
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Physical properties
Hardness: 3 (Mohs scale), Color: tan-yellowish, Luster: dull to earthy, Crystal Structure: Trigonal (often microscopic), Cleavage: Rhombohedral (not visible in grain), Specific Gravity: 2.5-2.7
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, and algal debris over millions of years. This specimen appears to be a clastic sedimentary rock composed of lithified carbonate sediment.
Uses & applications
Used widely in construction (aggregate), cement manufacturing, agriculture (as lime), and as a building stone. Also used in the steel and chemical industries.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is highly susceptible to acid rain and carbonation, which leads to the formation of caves and karst landscapes.
Field identification & locations
Identify in the field by testing with a drop of cold 10% hydrochloric acid; it will effervesce (fizz) vigorously. It feels gritty if it contains sand but generally has a softer feel than quartz-based rocks.
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