Jadeite

jadeite: see jade.

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jadeite

Uncut (left) and cut jadeite

(credit: Runk/Schoenberger—Grant Heilman)

Gem-quality silicate mineral in the pyroxene family that is one of the two forms of jade. Jadeite (imperial jade), sodium aluminum silicate (NaAlSi₂O₆), may contain impurities that give it a variety of colours: white, green, red, brown, and blue. The most highly prized variety is emerald green. Jadeite occurs only in metamorphic rocks, most often in those that have been subjected to the high pressures deep below the Earth's surface. The area around the city of Mogaung in northern Myanmar has long been the main source of gem-quality jadeite.

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jadeite [′jā‚dīt]

(mineralogy)

NaAl(SiO₃)₂A clinopyroxene mineral occurring as green, fibrous monoclinic crystals; the most valuable variety of jade.

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Jadeite 

a mineral belonging to the group of alkaline clinopyroxenes; a silicate of so-called chain structure. Its chemical composition is NaAl[Si₂O₆], and it contains slight admixtures of CaO, FeO, and MgO. It usually forms very dense, grainy, tough cryptocrystalline masses that range in color from white and bluish white to apple green. The coloring is often spotty. Jadeite is semitranslucent and very similar to nephrite. Its hardness on the mineralogical scale is 6.5–7.0, and its density is 3,300–3,400 kg/m³.

Jadeite is rare. It forms in alkaline metamorphic rocks and, less frequently, in contact-metamorphic complexes of rock associated with alkaline metasomatism. The largest known deposits are in Burma. In the USSR it is found in Kazakhstan and in the Pamirs. It is a valuable industrial stone, which has been used since ancient times for jewelry and artistic and decorative articles.