Silicate of sodium and aluminium. Jadeite is a member of the alkaline pyroxene group of minerals, and is so called because it is the source of one of the ornamental materials commonly known as jade, a word possibly derived from the Spanish ijada, or “flank,” due to its alleged therapeutic action on diseases of the kidneys. (People believed that if a piece of jade was worn close to the diseased organ, it had the power to cure it.)
Crystal system Monoclinic.
Appearance lt occurs as granular aggregates of small crystals, but has occasionally been found in crystals of a few centimeters. The color varies a great deal because of minimal differences in composition. As a rule it is off-while or grayish white, but it may be brown, yellowish brown, orange-yellow, reddish orange, lilac, blue-gray, or various shades of gray and green.
Physical properties lt has a hardness of 6.5-7, with extraordinary tenacity (the opposite of brittleness) for a mineral, especially one in which the tiny individual crystals sometimes display obvious cleavage traces. The density varies from approximately 3.30 to 3.36 g/cma but is usually 3.34 g/cm3. The very dark green variety can be as much as 3.40 g/cma. The refractive indices are ha 1.655 ny 1.667, but the massive material used for ornamenta purposes normally only gives one index, of about 166.
Genesis It is formed by regional metamorphism and occurs in lenticular masses or veins. It is also found as alluvial pebbles and even boulders.
Occurrence Jadeite comes mainly from northern Burma, where it IS recovered from rock rather than alluvium, yery small quantities of jadeite are also found in Japan’ Tibet, the United States (California), and Guatemala, where many items were made from it in antiquity. It is also found as small crystals in the Swiss Alps, even in crystals of a few centimeters.