Jade, or Nephrite, two names signifying "kidney-stone," applied to a very tough variety of hornblende (q.v.) from its supposed value in renal disease. This silicate of lime and magnesia is crypto-crystalline or compact, and has a hardness of 6.5; but its toughness is its most noticeable character. It varies in colour from white (allied to tremolite), with a specific gravity of 2.9, to dark green (allied to actinolite), with a specific gravity of 3.0. It occurs in boulders near Batongol, to the west of Lake Baikal, and very rarely in Europe; but in the Kuen-lun Mountains it forms veins in schists and gneisses. It also occurs in New Zealand, New Caledonia, and other Pacific islands, where it has long been used by the natives for axes, clubs, and ornaments. Jadeite (q.v.), chloromelanite, saussurite, fibrolite, amazon-stone, and bowenite have been confused with jade, but most of these substances are heavier than true jade.