fossil

Tumbled coral fragment (likely white calcitic coral)

Calcium carbonate, primarily aragonite or calcite (CaCO₃); exact coral genus cannot be determined from the image

AI-generated identification · may be incorrect

White, opaque, dull-to-waxy luster with small cavities and brown-orange staining; hardness about 3–4 Mohs, porous organic skeletal structure, and no obvious cleavage. It should effervesce with dilute hydrochloric acid or strong vinegar if carbonate-rich.

Identified August 13, 2026More fossil →

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Physical properties

Formation & geological history

Former marine coral skeleton, later lithified or preserved and rounded by abrasion; age may range from modern to fossil Cenozoic, but cannot be established visually. Common in shallow tropical reef environments and beach deposits.

Uses & applications

Used as a decorative or teaching specimen, bead, or aquarium material when responsibly sourced; not generally valuable as jewelry-grade material.

Geological facts

Coral skeletons are built by colonial animals and commonly preserve corallite pores or chambers. Some “white coral” sold commercially is dyed, bleached, or imitation ceramic/plastic.

Field identification & locations

Look for repeated tiny corallite patterns, irregular pores, carbonate reaction, and low hardness; distinguish it from porcelain, which is nonporous and does not react with acid. Common around tropical reefs and fossil-bearing limestones.