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cold has a repressive eftect. Always the gem is more beautiful on a
dark day, in an interior, with the light striking it sparingly. The
open day reduces its wonders to a if ghastly pallor, particularly the
air is chill and the sky cloudless.
The process of nature which forms opal is similar to that of
turquoise. Its hardness is 5.5 to 6.5, specific gravity 2 to 2.2, lustre
sub-vitreous.
For centuries the mines of Hungary were the main source of
the best quality. Not only was it harder, but the harlequin effect
under the slightly veiled, milky surface, was and still is, by jewelers,
greatly admired. The output is smaller than in the past, but it is
highly esteemed, for it is the most durable, with the smallest admixture
of water, of any in existence. But the Australian deposits are
gradually taking the place of the Hungarian, not only because they
are of almost as good quality, but are considerably more brilliant.
in subdued
The Hungarian is milk-white in body, with the colors,
shades, distributed irregularly in small patches. These pastel tints,
so greatly broken, compared to the superb rose, blue, green and
purple of the Australian, with its more uniform distribution over
larger areas, seem to the careless observer a bit tame, but they are
valued by experts as more rare. The body of the Australian has a
decided tinge of yellow, a good background for the bright, broad
flashes. Altogether it seems a more emotional stone.
There is a tremendous output of opal from Mexico, often ex-
tremely beautiful in play of color, blue and green predominating,
or Australian and in-
but it is less durable than the Hungarian
clined to fade.
An opal of interest is fire-opal, called by the ancient Mexicans
sun-opal, in deference to their god. This was first brought to Europe
by Alexander von Humboldt. In body color it ranges from yellowish
to brownish red.
The Empress Josephine possessed one of the finest fire-opals of
modern times. It was called the '
'Burning of Troy," from the
blaze on its surface. The obverse was opaque, a peculiarity of the
Honduras stone. Where is this wonder now?
In the American Museum of Natural History is a superb fire-
opal of deep luminous red, with an effect similar to crackled glass,
or frost work. This might well be the famous "Burning of Troy,"
except that it is less a sweep of flames than hot, glowing, scintillating
anthracite. If this fiery disturbance is due to flaws, as some
think, it is a glorious imperfection.
The most recent contribution to the market is the black opal
from Lightning Ridge, New South Wales, Australia, where it was
accidentally found, while mining the usual variety. Not all have
the black or very dark green body. Frequently it is gray, light or
dark, not so very different from normal opal, only with a more brilliant
contrast between the colors and the background. In the gem
stone, soft dim greens, purples and passionate reds move subtly in
the shadows, then flash forth with startling fire, yet in the main
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