sedimentary

Fossiliferous limestone (coquina-like shell limestone)

Calcite-rich bioclastic limestone, chiefly calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Visible shell and fossil fragments cemented in a gray-brown matrix; calcite has Mohs hardness 3, vitreous to dull luster, and trigonal crystal structure. Likely reacts with dilute acid, though the image alone cannot confirm composition.

Identified October 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Accumulated shells and other marine skeletal debris were compacted and cemented on a seafloor; age depends on the locality and cannot be determined from the image.

Uses & applications

Used as building and decorative stone, aggregate, and—where suitable—as a source of lime and cement.

Geological facts

The abundant visible shell fragments indicate a bioclastic rock; especially loosely cemented shell-rich limestone is called coquina.

Field identification & locations

Look for recognizable shell shapes and test a fresh surface for fizz with dilute acid. Fossiliferous limestone occurs in marine sedimentary basins worldwide.