Though most people associate jade with green, it can in fact come in almost all colors - white, gray, yellow, orange and violet are all pretty common. Highest quality jade, the so called "Imperial Jade", has a beautiful emerald color which comes from the metall chrome. Imperial Jade is found in Burma.
Jade is generally opaque to translucent, but it seldom has the transparency and shine prized by e.g emeralds.
Both jadeite and nephrite have been known to man for ages, although it wasn't until 1863 people understood that they are in fact two different minerals. Today jade is used mostly for jewelry and ornamental pieces. In older civilizations it was often used for weapons and knifes due to it's hardness. A thread-like structure coupled with a high density makes jade tougher than steel.
Jade can be found in the Far East and Central America, and jadeite is considered the more precious of the two minerals. It is quite difficult to tell the difference between jadeite and nephrite, which is why the collective name jade is still widely used.
Jadeite is seldom found alone, and is often mixed with the minerals albite and nepheline. They are however very different from jadeite, and not nearly as hard.
To create jadeite, one needs very high pressure and temperature; the kind that exists during continent collisions.
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