beauty.
In commerce it has a strange multiplicity of names ; now it is
adularla, again it is lunaria or moonstone, sun-stone, girasol, fish's
eye, water opal, or opal of Ceylon, according to the colours reflected.
From
Siberia we have a special quality which is of a yellow colour,
sprinkled over all the surface with an innumerable quantity of small
golden spots, produced by very small crevices in the lamina. The most
beautiful, cut invariably into smooth beads, have reflections in form
of a star, diverging from the centre, but are very rare. It is wrong to
confuse this species of adularla with the Oriental aventurino, because,
although it may have the same appearance, it has not similar hardness.
The adularla from Ceylon is generally in larger pieces than that from St. Gothard, but it is not so bright.
The
brilliancy and slightly bluish whiteness of the moon-stone (lunaria) of
Monte Stella are indescribable ; however, its value is diminished by
certain oblique lines which cross it internally.
It
does not appear that the ancients used this felspar, nor do I believe
that it can be engraved. Caire, nevertheless, asserts that Pini had a
head of Achilles engraved on a moon-stone by Grassi, and that it came
out with extraordinary effects. He believes, however, that the ancient
names of astrios, lapis specularis, and selenites, applied to this stone.
