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>> Group(s) : silicates
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Because of its perfect cleavage it is so named from the Greek "eu" for easy and "klasis" for breaking. It breaks into strips very easily. Colorless in general, it is in its blue variety that is mostly sought.

Exploited sites

It occurs in pegmatites, in geodes in Austria (alpine slots), Colombia, Brazil (Minas Gerais), Russia (Urals), India, Rhodesia, Tanzania, Zaire, Zimbabwe, China for its yellow variety.

See pictures of the mines / other pictures

Use in jewelry

The mineral is sought after by collectors especially if it is transparent and colored in blue or deep yellow, but it’s virtually impossible to cut because of its cleavage.

Daily care and precautions

more than sensitive to shocks, very fragile

Looking alike stones

afghanite , aquamarine , benitoite , beryl , iolite , kyanite , hiddenite , phenakite , sapphire , topaz

Historical healing properties

His influences are very similar to those of aquamarine, meaning uprightness, honesty, imposing a strict life, helping to generosity.

Imitations and treatments

can be colored in blue by radiation

Chemical characteristics

beryllium aluminum silicate mineral

Physical characteristics

Main color : blue

Other colors : colourless, yellow, green, purple

the most sought are blue, then colorless to blue-black

Color of streak : white

Luster : vitreous

Hardness : 7.5

Density : 3.05 to 3.20

Cleavage : perfect

Fracture : uneven

its cleavage makes it fragile

Optical properties

Transparency : transparent

Refractive Index : 1.650 - 1.678

Double refraction : 0.020

Definite, biaxial positive

visible double refraction : yes

Dispersion : 0.016 (0.009)

Pleochroism : very weak

Number of colors : 3

Light green, green yellow, green - blue

Absorption spectrum : 706 - 704 - 650 - 639

Fluorescence : none

Inclusions : gas bubbles in liquid-filled cavities and black inclusions


Slender prisms


Crystal system : monoclinic

Other informations

Astrological sign : Gemini, Libra