Naturalis historia 37.106

37.106

Indicae perlucent, crassiores sunt Arabicae. inveniuntur et circa Leucada Epiri et in Aegypto quae brattea aurea sublinuntur. et in his autem mares excitatius fulgent, feminae pigriores et crassius nitent. nec fuit alia gemma apud antiquos usu frequentior —hac certe apud Menandrum et Philemonem fabulae superbiunt—, nec ullae tralucentium tardius subfusae umore hebetantur, oleoque magis quam alio liquore.

CHAP. 31.—SARDA : FIVE VARIETIES OF IT. Sarda, on the other hand, is remarkably useful for this purpose; a stone which shares its name, in part, with sardonyx. It is a common stone, and was first found at Sardes, but the most esteemed kind is that of the vicinity of Babylon. When certain quarries are being worked, these stones are found, adhering, like a kind of heart, to the interior of the rock. This mineral, however, is said to be now extinct in Persia; though it is to be found in numerous other localities, Paros and Assos, for example.
In India there are three varieties of this stone; the red sarda, the one known as "pionia," from its thickness, and a third kind, beneath which they place a ground of silver tinsel. The Indian stones are transparent, those of Arabia being more opaque. There are some found also in the vicinity of Leucas in Epirus, and in Egypt, which have a ground placed beneath them of leaf gold. In the case of this stone, too, the male stone shines with a more attractive brilliancy than the female, which is of a thicker substance, and more opaque. Among the ancients there was no precious stone in more common use than this; at all events, it is this stone that is made so much parade of in the comedies of Menander and Philemon. No one, too, among the transparent stones is tarnished more speedily by exposure to moisture than this; though of all liquids, it is oil that acts the most readily upon it. Those stones which are like honey in colour, are generally disapproved of, and still more so, when they have the complexion of earthenware.