mineral

White aragonite (coralloid/botryoidal aragonite)

Aragonite, CaCO₃; orthorhombic polymorph of calcite

AI-generated identification · may be incorrect

Cream-white, waxy to pearly luster with branching, botryoidal and banded growth forms; Mohs hardness 3.5–4, specific gravity about 2.9–3.0, commonly translucent at thin edges. It has imperfect cleavage and effervesces vigorously in dilute hydrochloric acid.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms as low-temperature cave, spring, soil, or marine precipitate when calcium-rich water becomes supersaturated; specimens may be geologically young, though aragonite can occur in rocks of any age. Its delicate forms commonly develop by rapid mineral deposition around cavities or biological substrates.

Uses & applications

Used mainly as a collector specimen and occasionally as a calcium-carbonate ornamental material; it is less durable than calcite and not commonly used in jewelry.

Geological facts

The curved concentric patterns resemble coral or flowstone but are mineral growth textures. Aragonite is metastable at Earth’s surface and may slowly recrystallize into calcite over geological time.

Field identification & locations

Identify by its cauliflower-like branching habit, white color, hardness below glass, and acid reaction; calcite is similar but usually has rhombohedral cleavage. Common localities include Spain, Morocco, Mexico, Austria, and cave environments worldwide.