Jadeite is a translucent ornamental material, and has been carved since ancient times. Jade carving has flourished in China since 2000 BC, notably during the Chou dynasty and the Ch'ien-lung era of the Ch'ing dynasties. The Chinese have ascribed many human virtues to this gem. The Han scholar Hsu Shen, for example, asserted that its bright yet warm luster typified charity; its translucency, revealing inner color and markings, represented rectitude; its pure and penetrating note when struck displayed wisdom; its ability to break but not bend exemplified courage; and its sharp edges, not intended for violence, symbolized equity. Jade ornaments and tools also have been carved by the Mesoamerican Maya and Aztec, the Maori of New Zealand,the Alaskan Eskimo, and by inhabitants of India since the 17th century.
Jade consists of two separate silicate mineral species: nephrite, and the less common but more valued jadeite. Both are monoclinic. Nephrite has a splintery fracture, vitreous or silky luster, and dark-colored inclusions. A calcium and ferromagnesian silicate, nephrite is the massive form of actinolite and tremolite (see amphibole). It forms translucent-to-opaque, mottled-green, compact aggregates composed of interwoven long, thin fibers. Nephrite occurs in rocks subjected to low-grade metamorphism. Jadeite has a granular fracture, a glassy or pearly luster, and a pitted or polished surface. A pyroxene mineral, jadeite is a sodium aluminosilicate. It occurs as transparent-to-opaque compact lenses, veins, or nodules that vary in color due to impurities: the white through emerald- or apple-green, red, blue, and brown varieties contain calcium; the dark-green to blackish varieties (chloromelanite) contain iron. Jadeite occurs in rocks once subjected to deep-seated metamorphism and subsequently uplifted and eroded.