Aquamarine
Acquamarina
Be₃Al₂Si₆O₁₈ Properties
- Color
- Blue, blue-green, light blue
- Luster
- Vitreous
- Density
- 2.68–2.74 g/cm³
- Category
- Gem
Aquamarine is a variety of beryl with a sky-blue color that evokes seawater, from which it derives its name. It is the most common beryl gemstone after emerald and is valued for its exceptional transparency and large crystals.
The blue color derives from the presence of ferrous iron (Fe²⁺) in the crystal lattice. Heat treatment at 400°C transforms ferrous iron into ferric iron, eliminating greenish tones and producing a purer blue — standard practice in the gem trade.
The largest aquamarine ever found is the "Marta Rocha" from Brazil: 110 kg of rough crystal, from which over 300,000 carats of finished gemstones were obtained.
Belongs to the beryl group, the same mineral as emerald. Hexagonal system, space group P6/mcc. The refractive index is 1.567–1.590, birefringence 0.005–0.009. Unlike emerald, aquamarine typically has very few inclusions and high clarity. Absorption spectrum with band at 427 nm (Fe²⁺).
Mining localities
- Minas Gerais, Brasile (principale produttore)
- Pakistan (Gilgit-Baltistan)
- Madagascar
- Nigeria
- Mozambico
