Euclase (Colombia)

Euclase from Marine Mine, Colombia


Derived from the Greek word “eu” well and “klasis” break; showing internal cracks that cause its characteristic glow, highlighting the features of this gem.

Geological Origin

The euclase is found mainly in granitic pegmatites within greisen deposits and in the chlorite-schist ones associated with topaz.


Among the most important deposits are the ones in Brazil (Gerais Mine), Russia (Urals), Republic of Congo, Zimbabwe, and Tanzania. Colombia produces euclase in small amounts but of good quality.

Euclase Characteristics and Properties

Mineral Type Group IX Silicates
Color Colorless, sea green, light blue, dark blue
Streak White
Hardness 7.5 Mohs
Specific Gravity 3.10
Cleavage Perfect
Fracture Conchoidal
Crystal System Monoclinic
Habit Elongated striated prisms
Chemical Formula BeAl[OH l SiO4]
Optical Properties Biaxial (+)
Transparency Transparent
Luster Vitreous
Refractive Index 1.650 – 1.677
Birefringence 0.019 a 0.025
Dispersion 0.016 (BG), 0.09 (CF)
Pleochroism Very weak,green white, green yellow, green blue
Fluorescence Weak or none

Euclase False Names

The euclase can usually be confused with the aquamarine, the beryl, the hiddenite, and the sapphire. Due to its low hardness, the euclase is a difficult gem to cut and polish. It is recommended to be identified by their high birefringence.


Given its rarity it is a gem collection. Also, since 20% of the gem is beryllium it is acquired in order to combine it with different types of alloys to generate electrical wiring.