sedimentary

Crushed Limestone

Sedimentary Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Grey, white, or tan; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: Perfect rhombohedral (rarely visible in aggregate samples); Specific gravity: 2.3 to 2.7.

Hardness: 3 on Mohs scale
Color: Grey, white, or tan
Luster: Dull to earthy

Identified June 2, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. Most limestone is organic in origin, though some precipitates chemically from seawater.

Uses & applications

Primary use is in construction as road base, aggregate for concrete, and railroad ballast. Also used as a flux in steel making, a soil conditioner in agriculture, and in the production of cement and lime.

Geological facts

Limestone covers approximately 10% of the Earth's land surface. It is the primary rock type found in 'Karst' topography, characterized by caves, sinkholes, and underground drainage systems.

Field identification & locations

Can be identified in the field by its softness (scratched by a copper penny or steel knife) and its reaction to dilute hydrochloric acid (it will fizz or effervesce). Common in sedimentary basins worldwide.