Class : Silicate
    Subclass : Cyclosilicate
    Crystal system : Hexagonal
    Chemistry : Be₃Al₂Si₆O₁₈
    Rarity : Common

Aquamarine is a transparent to translucent variety of beryl from pegmatites. Its blue-green to blue color is due to iron that it contains in trace. Its name comes from the Latin aqua (water) and marina (marine) because of its color reminds the ocean. It is a mineral known since Antiquity. Aquamarine crystallizes in elongated prisms with hexagonal sections, sometimes bevelled often with flat terminations. It is a mineral variety with a strong importance for jewelery. It is extremely appreciated and used despite of a relative fragility.

In France aquamarine is present in some pegmatites of Limousin : crystals of 5 cm have been reported in Chanteloube Haute-Vienne.


Note also the huge stony but bluish Beryl pegmatites of Biauchaud at St-Pierre la Bourlhonne in Puy-de-Dome (photo on the left), where aquamarine is associated with schorl in a massive quartz.


We also find aquamarine more anecdotally in micro-crystals in the La Lauzière Massif, in French Alps.

Beryls and especially aquamarine never present twinning but some inclusions can be spectacular. We note especially a series of fluid or gaseous inclusions called "helicoidal" or "spiral" inclusions propagating on the axis of elongation of the crystal (photo right). These characteristic inclusions of beryls are due to rapid growth by "screw dislocation" along the axis of elongation.

Because of the importance of aquamarine in jewelry, it is a gemstone that is widely treated. Indeed in nature, the crystals are generally near colorless. To remedy this "problem", aquamarine is very largely heated to improve the color, this treatment is impossible to detect without advanced laboratory equipment. Generally in the market, gemstones with a bright color without inclusion are usually all treated.

Finally in the same way like emerald, aquamarine can be synthesized in laboratory, characteristic chevrons inclusions, visible under magnification, but only an expert eye can locate them. Further investigations based on the isotopy of oxygen allow to make the difference.