The name jade is applied to two distinct minerals: nephrite (a silicate of magnesia) and jadeite (a silicate of alumina) both extremely hard and usually green in color, a condition caused by the presence of iron. In a pure state, both jadeite and nephrite appear white, a condition so rare that white jade is considered priceless in the Orient. The more common hues of jade range from bright, emerald green (called Imperial jade), to spinach green, to a translucent golden yellow resembling the early Spring leaves, to blue, black and mottled. Though jade is found in the Western hemisphere and numerous Pre-Columbian treasures are carved from it, including ceremonial weapons, the stone enjoys its greatest popularity in China, where it is often worked for statues, jewelry, objets-de-vertu, musical chimes and amulets. For millennia, the Chinese have had a passion for fine jade and collectors will go to enormous lengths to acquire rare examples. The individual character of each piece of the mineral is particularly prized, and jade is frequently carved to show its variations to full advantage. As a talisman, besides its common use as a good-luck charm, jade is particularly valuable in helping those with intestinal problems, incurring kidney ailments and relieving heart palpitations. Yellow jade is also useful for diseases of the liver. Jade's popularity continues to grow today in both East and West.