Jade is an umbrella term for two different types of ornamental rocks used as jewelry, in jewelry or for ornaments. Jade is often referred to by either of two different silicate mineral names: nephrite (a silicate of calcium and magnesium in the amphibole group of minerals), or jadeite (a silicate of sodium and aluminum in the pyroxene group of minerals). Nephrite is typically green, although may be yellow, white or black. Jadeite varies from white or near-colorless, through various shades of green (including an emerald green, termed 'imperial'), to lavender, yellow, orange, brown and black. Rarely it may be blue. However these names are mineralogically incorrect. Both the amphibole jade (nephrite) and pyroxene jade are actually mineral aggregates (rocks) rather than mineral species and thus should not be described by mineral species names. Nephrite was deprecated by the International Mineralogical Association as a mineral species name in 1978 (replaced by tremolite). This makes the name "nephrite" mineralogically correct for referring to the rock. As for jadeite, since this is a legitimate mineral species, its name should not be used for the pyroxene jade rock. In China, the name jadeite has been replaced with fei cui, the traditional Chinese name for this gem that was in use long before Damour created the name in 1863. Jade is well known for its ornamental use in East Asian, South Asian, and Southeast Asian art. It is commonly used in Latin America, such as Mexico and Guatemala. The use of jade in Mesoamerica for symbolic and ideological ritual was influenced by its rarity and value among pre-Columbian Mesoamerican cultures, such as the Olmecs, the Maya, and other ancient civilizations of the Valley of Mexico. Source: Wikipedia (en)