Euclase

Euclase is a rather rare mineral of the nesosilicates class.
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euklas euclase
Colourless euclase from Brazil

Origin of name: firstly described in 1792 by French mineralogist René-Just Haüy who named it euclase, from Greek εὐ- eu- „good“ and κλάσις klásis „fracture“, because of its perfect cleavage

Synonyms and trade names: none

Can be confused with: many other gem stones of similar colour

Localities: mindat.org lists 128 localities (2024). Commercially important sources are in Colombia where fine blue specimens have been found. In Austria 17 deposits in Carinthia, Salzburg and the Tyrol are known.

Handling: euclase is sufficiently hard but due to its perfect cleavage of limited use in jewellery. Unfortunately we know nothing about sensitivity towards acids, brines and/or high temperatures. If you have working experience with euclase, please let us know.

Euclase shop

Gemmological Properties of Euclase

Formula:
BeAl[OH|SiO4]
Crystal system:
monoclinic
Mohs hardness:
7.5
Specific gravity:
2.99 - 3.10, average 3.04
Refractive index:
1.652 - 1.671
Max. Birefringence:
0.019
Dispersion:
none (mindat), 0.016 (Webster)
Pleochroism:
distinct in deep blue specimens, otherweise weak to none
Luminiscence:
weak to none
Lustre:
vitreous
Cleavage:
perfect
Fracture:
conchoidal to uneven
Colour:
colourless, white, green, yellowish green, bluish green, blue