146 A POPULAR TREATISE ON GEMS.
In
the detritus on the banks of the Adolfskoi, no fewer than forty
diamonds have been found in the gold alluvium, only twenty feet above
the stratum in which the remains of mammoths and rhinoceroses are
found. Hence Humboldt has concluded that the formation of gold-veins,
and consequently of diamonds, is comparatively of recent date, and
scarcely anterior to the destruction of the mammoths. Sir Roderick
Murchison and M. Verneuil have been led to the same result by different
arguments.
GEOGRAPHICAL DISTEIBUTION.
The
locality of gems bears some highly interesting characters, inasmuch as
we may sometimes judge, from • their appearance, the climate of their
locality; and it seems as if the countries of«the torrid zone had been
particularly favored by nature in producing the most precious gems, or
that those hot-beds wrere more propitious to the formation
of the blossoms of the inorganic world. Comparing, for instance,
spinelles and zircons, from Siberia, with those of Ceylon and Peru, we
find the first to be dark and of an impure color, as if emblematic of a
cold, unfriendly, northern climate ; whereas the latter glitter with
full brilliancy, and possess all those properties and beauties for
which gems are so highly esteemed. Often, too, we find the gems
collected in particular countries, or isolated spots of our globe, such
as the most precious gems from the East Indies and Brazil, where,
singular enough, they occur with the precious metals; as, for instance,
the diamond in company with gold and platina in Brazil. Some of the
gems have likewise been hitherto discovered in a single spot on one
continent only, and are then exhausted'; such as the rubellite, in
Maine, United States; the iolite in • Connecticut, United States, and
the lazulite in Persia.
