Jade is a compact, opaque gemstone ranging in colour from dark green to almost white. The term is applied to specimens cut from the minerals jadeite and nephrite. Jadeite, the less common and more highly prized of the two minerals, is a silicate of sodium and aluminum, NaAl(SiO3)2, usually containing some iron, calcium, and magnesium. It belongs to the group of minerals called pyroxenes . Jadeite crystallizes in the monoclinic system but rarely occurs in distinct crystals and is usually found in fibrous, compact, massive aggregates. It has a hardness ranging from 6.5 to 7; it is extremely tough and difficult to break. The luster on fresh fracture is dull and waxlike, but polished jadeite has a vitreous luster. Jadeite is found chiefly in eastern Asia in Burma, as well as in sections of Tibet and southern China. Nephrite, a member of the amphibole group of minerals, is a silicate of calcium and magnesium, with a small amount of iron replacing part of the magnesium. It is a tough, compact variety of the mineral tremolite with a hardness of 6 to 6.5. Polished nephrite has an oily luster. It is found in Alaska, Mexico, New Zealand, Siberia, and Turkestan. Jade was used in ancient times for weapons, utensils, and ornaments. A variety of jade called axstone is used by the natives of the South Sea islands for making hatchets. Jade has always been prized by the Chinese and Japanese as the most precious of all stones, and the most beautiful specimens of carved jade in the form of ornamental pieces, such as vases, bowls, tablets, and statues, many of which are now museum pieces, were made in China. Jade is a highly valued gemstone used in jewelry.
Related terms: