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cave, and thus Nero may have discovered its value to his defective
eyes.
Moreover, green is a pleasant, restful color to look into, as we
all know, who have trees in our grounds, or green furnishings in our
homes. Nature knew what she was about when she made the earth
brown and vegetation green. If it were not so, if these two vast
surfaces were a strong scarlet or a hard blue, we might all go mad !
Even the sea has a powerful admixture of green, and the sky is not
without its ameliorating influence. It is reserved for man, and man
alone, to call forth garish tints to clash with Nature's endless harmony.
When she affects a strenuous hue, and this mostly in the
tropics, where it has a certain place, she uses it sparingly.
Emeralds were first brought to Europe in any quantity from
South America, at the end of the sixteenth century, and from then
till 1830 all emeralds in the market were from the mines of Colombia.
The spot pointed out to the Spaniards, on March 3rd, 1537, by the
Indians who had presented them with a gift of emeralds, is in the
neighborhood of Bogota. The deposit at this place, Somondoco,
whose wild, inaccessible heights caused the Spaniards to abandon
their works there, was in 1901 started up again by an English com-
pany, but as yet only second quality stones have been found.
About one hundred miles from Somondoco, another locality
richer and of greater importance was discovered, and is now the only
one in Colombia where fine emeralds are met with. One mine there
is named "Esmeralda" ; but the Indians are hostile, the climate un-
healthful, and the output limited. It is somewhat west of the celebrated
Muzo claims, more or less abandoned, about 94 miles northeast
of Bogota. In the face of all this, it is quite comprehensible why
the emerald is the most expensive of stones, when of the desired tint
and without marked defects. So seldom is it perfect, that "as rare
as an emerald without a flaw" has passed into a saying. While easily
imitated in glass and doublets, the emerald so far has defied "recon-
struction," another factor in its ever-increasing scarcity and cost.
The cost is all the more amazing when one realizes that its color for
these days, when soft olive prevails, is too intense that its lustre is
;
by no means brilliant and that it is the least durable of the orthodox
;
stones. When taken from the mines the mineral is said to be
precious
quite soft, like certain marbles, because of a large admixture of water,
but hardens with exposure to the air. In gem form the hardness is
something less than true topaz and not much greater than garnet
7.5 to 8. Its specific gravity is 2.65 to 2.75, hardly more than quartz,
and its lustre vitreous to resinous. Its composition is silica 68 ; alumina
15 to 20; glucina 11 to 14. The coloring matter is due to chromium,
which with various affinities produces widely varying hues.
In form, when placed on the market, it is usually step-cut, the
rich green being most effective thereby ; but when sufficiently clear, it
is cut brilliant, and when clouded or defective shows best en cabochon.
Pliny says it was universally agreed not to engrave so valuable
a stone. Engraved emeralds are the rarest of the rare.
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