sedimentary
Limestone Fragment
Sedimentary rock (primarily Calcium Carbonate, CaCO3)
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
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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.
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