highly esteemed in the Middle Ages for its remarkable properties, and was believed to grow pale when worn by a sickly
person, and to change its colors with the hours of the day, a
superstition alluded to by Ben Jonson in his " Sejanus " : —
" Observe him as his watch observes his clock
And, true as turquoise in the dear lord's ring,
Look well or ill with him."
It was believed to give warning to its owner of an approaching calamity. Dr. Donne says :—
" As a compassionate turquoise doth tell,
By looking pale, the wearer is not well."
Shakspeare represents Shylock as saying he would not have
lost his turquoise for "a whole wilderness of monkeys."
Both the callais and the callaina of Pliny have been thought
to be identical with the modern turquoise, since they correspond
in some characteristics to it ; the callaina, of a pale green color,
found among the rocks of Mount Caucasus and in Carmenia
(Persia), yielded the best quality. This naturalist relates the
curious story that the Persians were accustomed to obtain the
turquoise from the inaccessible heights of their precipitous
mountains by shooting arrows to detach it from the projecting
cliffs and bring it within reach. Theophrastus mentions a
fossil ivory with variegated colors of white and blue, probably
odontolite, which was used very extensively by the jewellers of
his time, as it is by those of the present day. Modern turquoise is sometimes called callaite, or callainite, from the
callais of Pliny, but this mineral species, though it resembles
turquoise in colors, yet differs from it in composition and some
of its properties, being inferior in hardness and specific gravity.
Inscriptions, consisting of texts from the Koran, both in
Persian and Arabic, were cut on turquoise, but engravings on
