The term ‘jade’ and the Chinese term ‘yu’ have often been used loosely to designate a variety of hardstones. Their use should, however, be limited to jadeite and nephrite. Nephrite belongs to the amphibole group of minerals and is a silicate of calcium and magnesium. Its crystalline structure has the appearance of hair-like fibers felted together to form a closely integrated mass, and it is this which gives it its strength. Nephrite ranks as 6.5 on the Moh scale of hardness. Nephrite has been worked in China since the Neolithic period. Much of the nephrite used in China came from Khotan and Yarkand in Central Asia.
Jadeite is classed as a pyroxene and is a silicate of sodium and aluminum. It is a cryptocrystalline mineral and its minute crystals are interlocked to form a compact aggregate. It ranks 6.75 or 7 on the Moh scale of hardness. Chinese lapidaries do not appear to have worked with jadeite on a regular basis until the Qing dynasty. Most of the jadeite used in China came from the region around Tawmaw in Upper Burma. While both nephrite and jadeite are found in a range of different colors, depending the presence of small quantities of iron, chromium or magnesium, the brilliant green stones used in fine Chinese jewelry are jadeite.
Literally translates as “chicken-wing wood” because of the jagged, feather-like pattern of the grain. This hardwood ranges in tone between brown and gray. As this wood and its relatives are indigenous to Hainan Island, the furniture of the neighboring Fujian region are commonly made from jichimu.
265-420 and comprising Western Jin, 265-317 and Eastern Jin, 317-420.