colour of euclasio varies from green to blue in multiplied gradations
of tints, and on this account it might be placed amongst beryls, were
it not for the glucine it contains, which assimilates it more to the
emerald. It becomes electrical by friction and increases its cleavages.
was from the beginning considered a green topaz, but it is
distinguished from it by being more fragile and having less specific
weight, not reaching to 2-9.
It has double refraction, and under the action of the blow-pipe becomes opaque, and changes into a kind of blue enamel.