Collection: Aragonite

Aragonite is a calcium carbonate mineral with the chemical formula CaCO₃ , like calcite. It is a polymorph of the latter, meaning they have the same chemical composition but a different crystal structure . Here's a closer look at aragonite:

🔷 Properties of aragonite

• Chemical formula: CaCO₃

• Crystal system: orthorhombic

• Hardness (Mohs scale): 3.5–4

• Density: about 2.9 g/cm³

• Color: white, colorless, sometimes tinted (yellow, blue, green, pink)

• Luster: Vitreous to pearly

• Fracture: conchoidal to irregular

🔷 Origin and training

Aragonite forms in:

• marine environments , by chemical precipitation or biological activity (corals, molluscs);

• caves , in the form of stalactites and stalagmites (in competition with calcite)

• hot springs , rich in calcium;

• hydrothermal areas .

Its formation is favored by higher temperatures and pressures than those that favor calcite.

🔷 Use and interest

• Jewelry and Ornaments: Aragonite can be cut or polished, but it is fragile.

• Earth sciences and paleontology: it is found in fossil shells; its presence provides information on paleoenvironmental conditions.

• Industry: Sometimes used as a source of calcium carbonate, but calcite is preferred.

🔷 Transformations

Aragonite is metastable at room temperature:
👉 over time it can transform into calcite , which is more stable in Earth's surface conditions.

🔷 Notable examples

• Mother-of-pearl (mollusk shells) is often formed from aragonite organized into thin layers.

• Natural pearls are composed of aragonite and conchiolin.