What is Jade? - Metamorphic Rocks
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What is Jade?

Jade rock from Alaska

Jade is really two kinds of metamorphic rock, jadeite and nephrite, that look pretty much exactly the same. Scientists can tell them apart using chemical tests and x-rays. Like quartz, both jadeite and nephrite are chains of silicon and oxygen atoms.

Jadeite is a simpler chain and nephrite is a double chain. A trace of iron in the jade makes it look green (the same way iron makes the blood in your veins look bluish). Sometimes chromium makes the green color instead.

Jade forms where two tectonic plates meet and there's a lot of pressure under the earth. The pressure compresses a rock called pyroxene and transforms it into crystals of jade. There's a lot of jade in China, and artists in China used jade to make sculptures and jewelry from the Stone Age right up to modern times.

In Europe, jade was very rare and expensive. Doctors in Spain in the 1500s AD thought putting jade stones on your kidneys would help cure kidney disease. Our word "jade" comes from the Spanish word for kidneys, and "nephrite", another word for jade, comes from the Latin word for kidneys (because some fancier doctors used the Latin word).

Learn by doing: finding different kinds of rocks
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Bibliography and further reading about rocks:

More about different kinds of rocks
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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