Aragonite Crystal

Aragonite is one of nature's most distinctive calcium carbonate minerals — the same chemistry as calcite (CaCO3), but built on an orthorhombic crystal structure that produces entirely different forms. The star-shaped clusters this collection is known for come from Morocco, where cyclic twinning creates radiating pseudo-hexagonal "sputnik" formations you won't see in any other mineral. Every specimen here is hand-selected, individually photographed, and exactly what you receive. Pair one with a crystal cluster or display it alongside other Moroccan minerals from the same region.

Banded aragonite polished to a sphere, the layers recording successive stages of deposition — shop this piece

About Aragonite

Aragonite was named in 1797 after Molina de Aragón in Guadalajara, Spain, where classic twinned crystals were first studied. It forms in low-temperature environments: hot spring deposits, evaporite beds, and the oxidation zones of ore deposits. It is also one of the most important biogenic minerals on Earth — mollusk shells, coral skeletons, and the nacre (mother-of-pearl) lining of pearl oysters are all built from aragonite. Over geological time, aragonite slowly converts to calcite, its more stable polymorph, which is why well-crystallized specimens are prized by collectors.

The famous reddish-brown star clusters from Sefrou and Tazouta, Morocco, owe their color to iron inclusions and their geometry to cyclic twinning: six individual crystals intergrown around a central axis, mimicking hexagonal symmetry that aragonite's orthorhombic system doesn't actually possess.

How to Care for Aragonite

At Mohs 3.5–4, aragonite is a soft mineral. Keep it away from harder stones that could scratch it, avoid acids (it will fizz and etch, like all carbonates), and dust with a soft dry brush rather than washing. Display pieces away from prolonged direct water exposure.

Frequently Asked Questions

What is the difference between aragonite and calcite?

Aragonite and calcite are polymorphs: both are calcium carbonate (CaCO3), but aragonite crystallizes in the orthorhombic system while calcite is trigonal. This gives aragonite its characteristic needle-like, columnar, and radiating star forms, whereas calcite tends toward rhombohedrons and scalenohedrons. Aragonite is also slightly denser and marginally harder.

Why are aragonite clusters star-shaped?

The star or "sputnik" shape comes from cyclic twinning. Six crystal individuals grow intergrown around a shared axis, radiating outward in a pseudo-hexagonal pattern. This twinning habit is a signature of aragonite from Morocco's Sefrou region and makes each cluster geometrically unique.

Where does aragonite come from?

The classic star clusters come from Sefrou and Tazouta, Morocco. The mineral's type locality is Molina de Aragón, Spain, which gave aragonite its name in 1797. Notable specimens also come from Sicily, Austria, and New Mexico, and aragonite forms biogenically in seashells and coral worldwide.

How should I care for aragonite?

Handle it gently — at Mohs 3.5–4 it scratches easily. Never clean it with acids or harsh chemicals, keep it out of prolonged water contact, and dust with a soft dry brush. Store or display it where harder minerals won't rub against it.