sedimentary

Limestone (specifically Carboniferous Limestone)

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray to bluish-gray; Luster: Dull to earthy; Crystal structure: Trigonal/Microcrystalline; Specific gravity: 2.7

Hardness: 3 on Mohs scale
Color: Gray to bluish-gray
Luster: Dull to earthy

Identified June 8, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Gray to bluish-gray; Luster: Dull to earthy; Crystal structure: Trigonal/Microcrystalline; Specific gravity: 2.7

Formation & geological history

Formed in warm, shallow marine environments through the accumulation of shell, coral, and algal debris. The gray color and texture are typical of Carboniferous aged deposits (approx. 300-360 million years old).

Uses & applications

Used primarily in construction for building stone, aggregate for concrete, manufacture of cement, and as a soil conditioner in agriculture.

Geological facts

Limestone often contains invisible micro-fossils and can be tested for identity using weak acid like vinegar, which will make it effervesce or fizz.

Field identification & locations

Identify in the field by its gray color, presence of calcite veins (white streaks), and its ability to be scratched by a steel nail. Found worldwide in ancient marine basins.