of
the Nile, in Nubia, Nova Scotia, the TJqited States, (in Connecticut,
Massachusetts, Pennsylvania, Ohio, New-Jersey,. Missouri, Florida,) and
in other countries; but the best specimens are brought from Oberstein,
Iceland, and the Faroe Islands.
The
finest specimens are employed in jewelry, for rings, pins, bracelets,
necklaces, and seals ; the more common for snuff-boxes, vases, buttons,
&c. The larger masses are cut by means of a copper wire, with emery
and oil on a copper wheel; they are polished on a tin plate with rotten
stone, putty-powder, and pumice stone. The cutting is generally done on
a large scale, like that of agate. Many are susceptible of receiving
figures artificially, by means of the nitrate of silver. By Oriental
chalcedony is generally understood the better qualities ; those
chalcedonies of two or three divisions, called onyx, are used for
cameos.
The
value of the chalcedony depends on its quality, such as purity, color,
and the figures and drawings displayed on it; and among all the
varieties of chalcedony, the mocha stone stands the highest in price,
and also the onyx, which is principally employed for cutting cameos,
and according to its size, commands a high or low price. Mocha stones
are sold in France at from five to eight francs. The cabinet of
Dresden contains a plate of onyx, about three inches broad and long,
which is estimated at twenty-five thousand dollars.
CARNELIAN.
This
stone Was known to the ancients by the name of Sarda; which, according
to some, is derived from a place in Lybia or Sardinia, or, according to
others, from the Arabic word sarda, meaning yellow; it has been employed very frequently for cutting intaglios or bas-relief gems.
Carnelian occurs massive or in pebbles; its fracture is con-
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