sedimentary

Limestone with possible fossil inclusions

Sedimentary Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs scale); Color: Grayish-white to tan; Luster: Dull, earthy; Structure: Fine-grained clastic/biogenic; Cleavage: None (conchoidal fracture profile); Reacts with diluted hydrochloric acid.

Hardness: 3-4 (Mohs scale)
Color: Grayish-white to tan
Luster: Dull, earthy

Identified July 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow marine environments from the accumulation of shell, coral, algal, and fecal debris over millions of years. This specimen shows water-worn rounding, likely from a river or beach environment.

Uses & applications

Primarily used in construction (building stone/aggregate), cement manufacturing, soil conditioning in agriculture, and as a source of industrial lime.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It often contains microfossils or larger visible imprints of prehistoric marine life.

Field identification & locations

Identify in the field by its softness (can be scratched by a steel nail/penny) and its effervescence when exposed to weak acid. Found globally in areas that were once prehistoric seabeds.