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Jade: first observations
Jade is the collective term for two stones: jadeite and nephrite. Chemically, they are different, but are both silicates: jadeite a silicate of sodium and aluminum, while nephrite is a silicate of calcium and magnesium. Nephrite has the longer documented history-going back over 7000 years, while jadeite is a relative newcomer in that its important mining history goes back to about the middle of the 18th century (in Burma: Guatemalan dates are different). Today, when one speaks of "jade, the stone of heaven", one is speaking about nephrite; when discussing jade, the rare and valuable gemstone used in jewelry, that is usually jadeite. Although quite similar in hardness, specific gravity and toughness, nephrite is in the amphibole group, while jadeite is a pyroxene. Suffice it to say that the chemical differences were first identified and published by the Frenchman D'Amour in 1863. The colors in which they appear are vastly different, however. More on that later. Interestingly, both terms derive from the observation that jade is somehow "good for the loins." Nephrite comes from "lapis nephriticus", Greek for "kidney stone". It was believed that this stone, when worn close to the skin, would act to protect the kidney. "Jadeite" was derived from the Spanish spoken by the conquerors of Central America, where jade was highly prized. They were told that the stone had curative powers for diseases "of the loins" and so they called it "piedra de ijada", Spanish for "stone of the flanks."This was translated by D'Amour" into French as "pierre de l'ejade" which was transformed by a linguistic process known as "back formation" to "le jade", and then came into English as 'jade". Back to News List |