sedimentary

Limestone Fragment

Sedimentary rock (primarily Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale); Color: Off-white, grey, tan; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Fragmented; Specific Gravity: 2.5-2.7

Hardness: 3 (Mohs scale)
Color: Off-white, grey, tan
Luster: Dull to earthy

Identified June 2, 2026More sedimentary →

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Physical properties

Hardness: 3 (Mohs scale); Color: Off-white, grey, tan; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Fragmented; Specific Gravity: 2.5-2.7

Formation & geological history

Formed by the accumulation of shell, coral, algal, and fecal debris in marine environments; can also form via chemical precipitation from lake or ocean water.

Uses & applications

Primary source of lime for cement, used in road base, construction aggregate, agricultural soil treatment, and occasionally as dimension stone.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains fossils of ancient marine organisms.

Field identification & locations

Identified in the field by its softness (can be scratched by a copper coin) and its strong effervescent reaction when exposed to dilute hydrochloric acid.