Prase

Prase , an agate quartz, called also chrysoprase, is of an apple-green colour, passing rarely to a deep green; and more or less translucent, its fracture is dull and even.

Basalt

Basalt , a compact igneous rock of volcanic origin, and homogeneous appearance, the essential components of which are feldspar and pryoxene. When the latter occurs in crystals, the basalt is said to be porphyroid.

The ancients made great use of basalt in their monuments. The Egyptians, who fashioned it into statues, brought it from Ethiopia, and called it "lapis AEthiopica." In the Paris Cabinet of Medals, there is a bust of Scipio Africanus in green basalt.

Serpentine

Serpentine is an opaque talc steatite in close combination with iron, generally of a green colour inclining to black, and often mixed with spots. It should be carefully distinguished from certain varieties of jade or diallage.

Haematite

Haematite, a variety of red iron ore, which in its natural state is of a dull red colour, but when polished assumes a very decided metallic grey tint. The ancients engraved upon haematite, and the Babylonian cones and cylinders were chiefly composed of this substance. Hence it was most generally employed in the East, doubtless because credited with special virtues in the occult sciences.

Of the soft stones, the most commonly used are alabaster and agalma-tolite, already spoken of, besides filiate of lime or fluor-spar, of which the beautiful varieties, violet, lilac, jaspered and "dichro'ite," were cut into elegant vases, and associated with the gilt bronzes of Louis XVI.

The history of antique gems is one of the least difficult to restore. The reduced scale of the objects themselves has for the most part saved them from destruction. They have, so to say, buried themselves in the earth, overturned by social revolutions, and here it is, that the patient seeker still succeeds in finding them. Such as were not so buried, owed their preservation to another cause. In his work entitled "Delle cose gentilesche," Marangoni tells us, that the popes and bishops did not forbid the use of cameos and intagli of profane subjects in the decoration of sacred images and for treasures of the church. When, in the fourteenth century, Urban V. caused the heads of the apostles, SS. Peter and Paul, to be translated to the basilica of St. John Lateran, he caused magnificent reliquaries to be procured for them, and invited the co-operation of all the rulers of Christendom. Besides donations in money, many sent pearls and gems engraved with all manner of subjects. Thus it happened, that a head of Nero was placed upon the breast of one of the two reliquary busts.

In his "Voyage d'ltalie," Mabillon, also relates that he saw a silver cross bearing the images of Isis, Serapis, and a priest of Isis with a sistrum in his hand, besides the head of a Roman emperor. To these instances, Marangoni adds that of a gold cross preserved in the monastery of Ristich, on which was a stone with the figures of Venus, Jupiter, and Cupid. In opposition to the opinion of some writers, who attributed these facts to monkish ignorance, thus unknowingly associating heathen representations with the emblem of redemption, the Italian archaeologist maintains that they are to be regarded as brilliant witnesses to the degradation of idolatry, overthrown by the victorious standard of the Christian religion.

The apology does not lack ingenuity, and in any case it is at least certain that happy mistakes of this sort have rescued from destruction many works of the highest interest. Thus Jupiter and his eagle taken for St. John the Evangelist, the Apotheosis of Augustus regarded as the representation of the triumph of Joseph in Egypt, secured the safe keeping, in the Sainte Chapelle and the Chartres Cathedral, of the two most remarkable specimens of antique gem engraving at present to be found anywhere in France. In spite of its bacchanalian emblems, the agate tazza of the Ptolemies, as it is called, was transformed into a chalice for divine service in the basilica of St. Denis, when it was presented to that church in the Carlovingian epoch.

It forms no part of our plan to describe these precious remains of classic art. Connoisseurs desirous of studying them must patiently explore the collections in the public museums; for a work devoted specially to the subject, would scarcely enable the reader to appreciate the differences of style and workmanship distinguishing the various schools, or to recognise the touch of the most illustrious artists. It must not be forgotten that, notwithstanding the wealth of public and private collections, many celebrated stones mentioned in history have long disappeared. The only means often available for judging of their merit were the copies, or, better still, the glass paste imitations, kinds of contemporary castings, intended to enhance the renown of these objects, if not to the benefit of their authors, at least to satisfy the vanity of their owners. So many, even of the most important of these works of the glyptic art, have remained anonymous, that no attempt has ever been made to assign them to definite artists. What analogies are there in the workmanship of the Cup of the Ptolemies, the Sainte Chapel le agate, and other similar marvels, without prototypes or subsequent imitations, by which a conjecture might be hazarded as to their authorship? To dwell on the firmness of touch, the surpassing elegance of design, the grand character of the Greek engravings, or to speak of the Roman as an epoch of relative decadence, throws no light on the subject, because Greek art itself had its various epochs of splendour and decay, and, no less than the Roman school, produced artists of varying merit. To venture an opinion on antiques, whether gems or medals, requires a special tact, an inborn taste educated by study and a systematic comparison of typical monuments.