It rarely happens that Pliny gives any information as to particular jewels, almost all his notices of precious stones being confined to descriptions of their form and color, and data regarding what was popularly believed as to their talismanic or therapeutic power. In the case of the _opalus_, however, he writes as follows: “There exists to-day a gem of this kind, on account of which the senator Nonius was proscribed by Antony. Seeking safety in flight, he took with him of all his possessions this ring alone, which it is certain, was valued at 2,000,000 sesterces ($80,000).”[212] The stone was “as large as a hazel-nut.” This “opal of Nonius” would be the great historic opal if we had any assurance that it was really the stone to which we now give this name. As, however, the principal European source of supply in Hungary does not appear to have been available in classic times to the Romans, and as opals are not found in the places whence, according to Pliny, the _opalus_ was derived, we are almost forced to the conclusion that he had some other stone in mind when he gave his eloquent description of the _opalus_. And yet, in spite of all this, Pliny’s words so well describe the beauties of a fine opal that it is difficult to determine what other stone he could have meant. For it can well be said of opals that “There is in them a softer fire than in the carbuncle, there is the brilliant purple of the amethyst; there is the sea-green of the emerald—all shining together in incredible union. Some by their refulgent splendor rival the colors of the painters, others the flame of burning sulphur or of fire quickened by oil.”[213] Possibly some brilliant varieties of iridescent quartz—“iris” quartz, possessing an internal fracture, displays with great brilliancy all the colors of the rainbow, sparkling with wonderful clearness in its field of transparent mineral—might excite the admiration of one who had never seen an opal. Referring again to these quartz crystals, they are often cut so as to form a dome of quartz and are even used as distinct jewels. The fact that Pliny could praise the Indian imitations of the _opalus_ in glass, and could state that this stone was more successfully imitated than any other, is an almost decisive argument against identifying the _opalus_ with an opal, for it is well known that no stone is more difficult to imitate.