Euclase is very brittle, and therefore is rarely used as an ornamental
stone.
This mineral has the hardness of 7.5; specific gravity, 3.1; lustre,
vitreous to pearly; it is transparent to semi-transparent, doubly
refractive, is not acted upon by acids, fuses under the blow-pipe to a
white enamel, and is composed of:
Silica 41.2
Alumina 35.2
Glucina 17.4
Water 6.2
Euclase occurs in Brazil, in the neighborhood of Villa Rica, and also
in the Urals, in colorless, pale green, blue, pale yellow, and white
colors.