||THE BERYLS GROUP
Crystallization: hexagonal system
Basic chemical composition: aluminium basilicate and beryl
Basic chemical formula: 3BeO.Al2O3.6SiO2.
Hardness: from 7.5 to almost 8 .
Specific weight: from a minimum of 2,60 to a maximum of 2,91, generally about 2,70-2,72..
Refractíon index: (1.5680-1.6002) - (1.5632-1.5904).
Berefraction index: da 0.0048 a 0.0098.
Gemmological varieties: (green) emerald; (pink) morganite; (blue) aquamarine; (yellow, greenish-yellow) heliodor;(colorless) goschenite. All these varieties are differently colored thanks to very small quantities of chromogenous elements, generally metals, present in the stone crystalline structure
Besides what stated above which is effective for all beryls, it can be said that the color is due to the presence of iron oxide traces.
Major layers., Brasil, Russia and Madagascar, Less important are layers found in India, Pakistan, Australia, and Monzambique, Small crystals of rare beauty are found in that museum of mineralogy of Isola d'Elba, in Italy; generally they are inside of geodes, in the veins containing also the tourmalines.
Specific weight 2.69
Refraction index: 1.570-1.575
Berefraction index ; 0.005
Pleochroism: less clearlv visible in the pale colored stones, it?s more intense in the blue-green stones.
Colors: from blue to almost colorless, and a bright blue. There are aquamarines of a pale color tending towards green, that after heating (at a temperature slightly exceeding 400°C) change from green to blue. Certain stones represent a serious problem for some gemmology experts because sometimes they do not know how to define a stone. It?s our opinion, that it?s a typical example of things that are not worth arguing about, what?s important is that the stone is fine and natural; the name is secondary and unreal; remember this: on earth there are no stones perfectly similar.
Sizes: all the most important museum of mineralogy have large crystals of aquamarires. The greatest one is a crystal exceeding one hundred kilos.!
Similar gems: zircon, sapphire, topaz (naturaland bombè), blue tourmaline, euclase, blue spinel (natural and synthetic).
Imitation gems; vitreous paste and synthesis of stones having a similar aspect