A variety of onyx cut in such a manner that a zone of bluish white lies over a base of deep brown.
This name is from the diminutive of onyx, viz., onicolo, whence niccolo, and not from the name of a certain Nicolo, perhaps an artist of the sixteenth century, as some assert.
This stone, of little intrinsic worth, acquires value by being used in works of cameo and intaglio.
It may almost be said that niccolo is a kind of onyx agate which has an extraordinary fineness of texture.
Its specific weight is 2.090.
Everything leads us to believe that niccolo is the Egyptilla thus described by Pliny : AEgyptillam sacchus intelligit, per ahum sarda, nigroque vents transceuntibus : valgus autem in nigra radice cœruleum facit* It
was often used by the ancients ; this is proved by the works of
intaglio and relievo which have been found executed in this stone.
of this mineral is derived from the peculiar play of light refracted by
its surface, which resembles very strikingly the eye of the feline
race. * Caire, 260, note.