ONYX AND SARDONYX
ONYX
and sardonyx are varieties of agate with layers in even planes of
uniform thickness, thus adapting them to the purposes of cameo
engravers. The cameo has a base of one colour and the figure of
another. The art of cameo engraving attained a point nearest perfection
with the ancient Romans, evidence being supplied by the numerous
relics, that are the admiration of modern artists. The word onyx means
a finger-nail, and was suggested, it is supposed, by a fancied
resemblance to the lustre and appearance of a finger-nail. Of course
—if the Greek myth be true—this most beautiful instance of
stratification in all mineral nature owes its origin to the freak of
playful Cupid, and is the only visible and palpable evidence we have
of the mundane visits of the Goddess of Beauty.
Sardonyx is a variety of onyx in which one layer has the brown colour of sard. Chalce-
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