Aragonite: What It Is and How to Use It

Aragonite is a natural form of calcium carbonate that forms in shells, caves, and some hot springs. It looks similar to calcite but has a different crystal shape and often shows as needle-like or columnar clusters. People use aragonite in aquariums, as polished stones, and sometimes in jewelry. Want a simple way to tell it apart from other minerals? There are a few practical checks below.

Where Aragonite Comes From and How It Looks

Most aragonite forms in marine settings—think mollusk shells and coral skeletons. It also appears as cave deposits (speleothems) and as a product of hydrothermal activity. Color ranges from white and cream to brown, green, or even bluish tones when impurities are present. Fresh aragonite often feels a bit softer than calcite and breaks into curved or fibrous pieces rather than flat, smooth cleavages.

If you have a small sample, try a simple hardness test with a copper coin or a knife. Aragonite will scratch less easily than calcite but can still be scratched by a steel blade. Under a magnifier you may notice radiating needle-like crystals that give it a starburst or coral-like look. Those needle clusters are a pretty reliable ID hint.

Common Uses and Practical Tips

Aquarium hobbyists use aragonite sand and rubble to stabilize pH and supply calcium for corals and shell-building animals. It dissolves slowly, buffering water chemistry without sudden swings—useful if you keep a reef tank. For home displays, aragonite clusters look attractive in a simple glass bowl or on a shelf; keep them out of direct sun to avoid fading or heat stress that can cause cracking.

In jewelry, aragonite is usually cut into cabochons or left as polished freeform stones. It’s pretty but softer than many gem materials, so avoid rings or everyday pieces that face knocks. Clean aragonite with a soft cloth and mild soapy water—never use harsh chemicals or ultrasonic cleaners that can damage the structure.

Some sellers market aragonite as a health supplement or decorative wellness stone. Treat those claims with caution: aragonite is a mineral source of calcium, but you should rely on proven supplements and medical advice for health needs. If you’re buying aragonite online, pick sellers who show clear photos, mention origin, and offer a return policy.

Finally, storing aragonite is simple: keep it dry, away from acidic cleaners, and wrapped in soft cloth if stacked with other stones. For aquarium use, rinse before adding to the tank to remove dust. With a little care, aragonite stays attractive and useful for years.