Jade.— This name is commonly used to designate both nephrite (a silicate of magnesium and calcium), and jadeite, named by Damour in 1863 (a silicate of aluminum and sodium). Nephrite has a hardness of 6.5, its specific grav ity being 2.8, while jadeite's hardness is 7 and its specific gravity 3.3. The Chinese name for jade is yu, or yu-shi; the most prized variety of iadeite is termed fei-tsui, °kingfisher-plumes,* jewel jade, or imperial jade. The jade brought by the Spaniards from the New World was named by them piedra de ijada, °stone of the flank,* whence our °jade)); it was asserted (and believed) to be a highly efficient remedy for diseases of the kidneys. This belief was reflected in the later name lapis nephriticus (kidney-stone) from the Greek nephros, °kidney,* the origin of our nephrite. A third stone of the jade group is chloromelanite, discovered by Damour in 1865. This mineral, with a hardness of over 6.5 to 7 and a specific gravity of 3.4, is of a darker green than jadeite (with which it is very closely related) because in its composition iron supplants a part of the alumina in the latter. A number of prehistoric ornamental objects of chloromelanite have been found in France, and a few in the lake dwellings of Switzerland, as well as in Mexico, Guatemala and Colombia. The chief source of supply for nephrite has been in modern times the Kuen-lun Mountain in eastern Turkestan, while the jadeite now mined comes from the Kachin Hills, about 120 miles from Mogaung, Upper Burma. The nephrite of New Zealand, called by the natives punamu, or °green-stone,* is also well known. Numerous jade artefacts made in prehistoric times have come to light in almost all parts of the world, although the source whence the stone was ob tained has not often been determined. For a time it was rather generally believed that none of it could be found in situ in Europe, and that the material for the European artefacts and for those discovered in the Americas as well was strictly of Asiatic origin. This erroneous idea has been entirely dissipated by several dis coveries of nephrite in its original place at various European localities. The largest mass ever extracted was found by the present writer in 1899 at Jordansmiihl, Silesia; it weighed 4,718 pounds (2,140 kilograms). This is in the Heber R. Bishop Collection in the Ameri can Museum of Natural History, New York City.
The fondness of the Chinese for jade is proverbial, and the finest ornamental objects (both of nephrite and ofjadeite) have been produced by Chinese lapidaries, although to Hindu and other Asiatic artists also may be credited admirable work, and in New Zealand, as well, the native nephrite has been quite skil fully carved, as in the case of the curious hei-tikis, grotesque ancestral heirlooms with which some superstitious fancies are associated. In hue, jade runs through the gamut of the dif ferent shades of green, from the darkest to the lightest; some specimens are quite white. Jadeite is occasionally almost transparent, of a rich emerald green Jewel jade or Imperial jade, when containing a greater quantity of iron or chromium with a specific gravity up to 3.6 is called chloromelanite.
The color, translucency, hardness, toughness and fine structure are the properties that have rendered jade a very attractive material for the most artistic lapidaries of China, India, ancient Mexico, France, Russia and other countries. The Chinese have been the most
pre-eminent in carving jade as is testified by the wonderful, beautiful and interesting carved objects in the Heber R. Bishop Collection in the Metropolitan Museum of Art, New York, and in the collections of the museums of Boston, Chicago, Paris, Berlin and Petrograd. The Russian objects are usually of stupendous size; the Chinese objects scarcely ever a foot high; some of the Russian works are from two to six feet long. Notable are the sarcophagus of Tsar Alexander II, and other work in the Imperial collections or among the Imperial gifts of the Russian tsars.
Nephrite is much tougher than jadeite, and as an illustration of its extraordinary toughness Dr. Heinrich Fischer relates* that he placed a large block of jade under a steam hammer, and that as a result of the blow the anvil on which the stone rested was broken, while the stone itself was unharmed. This illustrates the great difference between hardness and toughness, for although the diamond has a hardness of 10 against 6.5 of nephrite, the former would have been broken to splinters by such a test.
Owing to the shutting down of the European lapidary works due to the World War, the eastern Chinese lapidaries were called upon to supply the deficiency. The chromium-colored jadeite, because of its great beauty. has come into high favor, especially the rich translucent emerald green and yellowish green jewel-jade for bead necklaces, some of which have been sold for $20,000. Carved ornaments of jadeite have sold for from $500 to $2,000. Jade thumb rings were formerly bought by wealthy Chinese for from a few dollars to $15,000 each. The exports of Burmese jadeite in worked form from China during the five-year period 1914-18 have been valued at about $2,000,000.
Turquoise is a phosphate of lime colored with copper, found for many centuries in the Nishapur district, near Meshed, Persia, where it is highly valued and is sold in great quanti ties, from gems weighing many carats each to minute, round discs not more than one or two millimeters in diameter. It is found also in the Sinai Peninsula, where the mines were worked by the Egyptians almost as far back at 4000 a.c. The color is a more intense blue than that of any other stone. In China, where it is worked into Oriental objects, it is found in great masses, weighing many pounds each, but impure. Gem turquoise occurs also in New Mexico, Arizona, Nevada and California as well as in Mexico, and it was used by the pre Columbians for ornament as well as in mosaics in combination with various colored shells or obsidian and for the decoration of human skulls, daggers, clam shells and other objects. Many of these are of great beauty. As a ring stone the beautiful color of the best turquoise makes it a great favorite. In order to preserve the color, it is desirable to exercise care in subjecting turquoise to contact with liquids. In the Middle Ages, and later, the superstition prevailed that the wearer of a turquoise would be protected from injury by falls. In the 16th century this was called the Turkey stone, as it came to Europe from Persia via Turkey; the name was then converted to turquoise.