sedimentary

Porous coral limestone (possible fossil coral)

Bioclastic limestone, chiefly calcite (CaCO₃); coral identification is uncertain from the image

AI-generated identification · may be incorrect

Pale tan, irregular, porous and dull to slightly crystalline; calcite hardness 3 Mohs, rhombohedral crystal structure, with imperfect cleavage. The specimen’s small cavities and lumpy texture may reflect preserved or weathered skeletal material.

Identified October 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine carbonate shells and coral fragments accumulate and lithify in warm, shallow seas; age cannot be determined visually and may range from recent to ancient.

Uses & applications

Limestone is used in cement, lime, aggregate and building stone; attractive coral fossils are collected or displayed.

Geological facts

Acid fizzing on a fresh surface supports calcite-rich limestone, though avoid testing valuable specimens.

Field identification & locations

Look for repeating coral corallites or other organized fossil structures; this photo does not show enough detail to confirm them. Limestone is widespread in former marine regions.