sedimentary

Fossiliferous Limestone (with Coralline Inclusions)

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Grey/tan matrix with white fossilized structures; Luster: Dull or earthy; Crystal structure: Orthorhombic or Trigonal (crystal level); Cleavage: None (rhombohedral for calcite component).

Hardness: 3 on Mohs scale
Color: Grey/tan matrix with white fossilized structures
Luster: Dull or earthy

Identified April 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in warm, shallow marine environments from the accumulation of calcium-rich skeletal remains, shells, and coral. This specific piece appears to be a water-worn river or beach pebble where soft rock has eroded to reveal harder fossilized coral/skeletons.

Uses & applications

Used primarily in construction (gravel/cement), agriculture (lime), and as a common find for amateur fossil collectors.

Geological facts

Limestone covers about 10% of the Earth's total land surface. Many limestone deposits contain the history of ancient oceans, preserving organisms from millions of years ago.

Field identification & locations

Identify by its reaction (fizzing) when exposed to a weak acid like vinegar. Look for white, web-like or tubular structures within a grey rocky matrix, often found near coastlines or ancient lake beds.

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