The Agate is a variety of quartz found in different colours, often with alternate layers of red and white known as "ribbon" Agate, also of a milky white. The latter can be artificially coloured and, in consequence, is obtainable in bright greens and blues as well as in various tones of greyish purple.
The Moss Or Tree Agate is a variety ornamented by Nature in a most remarkable manner with lines, spots, and frequently with natural objects taking the distinct forms of ferns, trees, clouds, and moss, giving a very mysterious effect to the stone. In the days of the Romans this variety was held in high repute as possessing both medicinal and talismanic virtues, it being claimed that the wonderful markings formed in this stone indicated that it had been specially singled out by the Creator to receive wondrous occult power. According to Orpheus, "If thou wear a piece of Tree Agate upon thine hand the Immortal Gods shall be well pleased with thee; if the same be tied to the harness of thy oxen when ploughing, or about the ploughman's sturdy arm, wheat-crowned Ceres shall descend from heaven with full lap upon thy furrows".
The Moss Agate was also considered good for the sight and was used by physicians for palettes on which they ground down the ingredients used in making up lotions and ointments.
The vegetable representations in the Tree Agates are supposed to have been produced by particles of metallic substances, such as iron and magnesium; the name Mocha Stone, sometimes used to indicate this variety, is derived from Mocha in Arabia, where it was found.
In the British Museum there is a striking specimen of Moss Agate representing a likeness of the poet Chaucer; and the Strawberry Hill Collection has another with a portrait of Voltaire, and a third showing the profile of a woman. There are also numerous varieties of Agate dependent upon the arrangement of the layers; sometimes the stone shows parallel lines of light and dark tints, when it is called banded or ribbon Agate. When the colours are very sharp and defined it becomes Onyx Agate, and when the stripes converge towards the centre of the stone it is known as Eye Agate; whilst another variety showing many colours becomes Rainbow or Iris Agate.
According to Mr. Streeter, Agates in their natural state are formed in the cavities of rocks, and it is conjectured that when the rocks were in a fluid state the Agates were formed by the escape of gas or steam. These cavities were afterwards filled with some mineral substance, such as silica, held in solution and deposited on the interior walls of these receptacles, forming a kind of geode.
In addition to the Moss or Tree Agate, the Greeks and Romans had great faith in the talis-manic and medicinal virtues of all other Agates, wearing them to avert sickness, regarding them particularly as an antidote to the bite of an Asp, if taken powdered in wine, or as an infallible cure for the sting of a Scorpion if tied over the wound. They also brought success in love and friendship, great gain, and the favours of the great, if strung on a hair taken from a lion's mane.
Pliny was a great believer in the virtues of the Agate, and writes that storms may be averted by burning these stones; whilst Camillo Leonardo, in addition to their power to avert lightning and tempest, says they bring strength, vigour, and great success to their wearers. Marbodus, Bishop of Rennes, ascribes the escape of Aeneas from all his perils to the virtue of an Agate Talisman which he always carried with him.
Although these stones eventually ceased to be in much demand for signets amongst the Romans, they never lost their popularity as Talismans, and were in great request, not only amongst the Latin races, but also among the Persians and peoples of the Orient, amongst whom it was universally believed to confer eloquence, to enlighten the mind, to allay fevers, also to bring luck in connection with wills and legacies, to sharpen the sight, aid in the discovery of treasure, and make its wearer amiable and agreeable.
Amongst Mohammedans it was believed to cure insanity if taken powdered in apple juice. In Elizabethan days our forefathers had great faith in its talismanic virtues, the Queen having amongst her jewels a large oval Agate engraved with scenes representing Vulcan at his forge with Venus looking on. This jewel was presented to her by Archbishop Parker, and was accompanied by a parchment giving in Latin a long list of its properties, concluding to the effect that as long as Her Majesty possessed this jewel she would ever have a trusty friend.
Agates of all kinds were much esteemed by the Greeks, particularly those specimens in which could be traced resemblances to natural objects. The following verse poetically describes its many qualities:
"Who comes with summer to this earth And owes to June her day of birth, With ring of Agate on her hand Can Health, Wealth and long life command".