Agates are divided naturally into two varieties:—
Agates of a single tint. Agates of several tints.
FIRST VARIETY.
Chalcedony.—The chalcedony is quite a common stone, of a dull or milky-white; and sometimes of a bluish tint, when it is called saphirine.
The
ancients obtained chalcedony from Egypt and Syria, and it was an object
of considerable commerce at Carthage. It probably derived its modern
designation from KarchedSn, the Greek name for Carthage. It is found in
England, Ireland, Germany, Italy, &c.
Chrysoprase.—Chalcedony
coloured by the oxide of nickel, varying in colour from deep verdigris
to the palest green. It takes a very beautiful polish, and fifty years
ago was fashionable in jewelry, though now quite forgotten.
Cacholong.—A
variety of chalcedony of a whitish tint, cloudy almost to opacity. It
is found in Bokhara, Ireland, Greenland, and the Faroe Islands.
Cornelian.—A
species of chalcedony, but of a finer grain. The ancients confounded it
with the sardoine, and it was not until the thirteenth century, in the
writings of Albertus Magnus, that the distinction became established.
