Nephrite

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Nephrite
Chemical composition Complex Ca Mg/Fe (calcium magnesium/iron) silicate
Crystal system Monoclinic
Habit Polycrystalline
Fracture Splintery
Hardness 6.5
Refractive index ±1.62
Specific gravity 2.90 - 3.20
Lustre Greasy to vitreous

Nephrite has been recognized as a separate type of jade since 1863. It is formed from aggregates of fibrous amphibole crystals. The structure they form is interlocking and tougher than steel. It's colors range from dark green iron rich varieties to cream colored magnesium rich varieties. It can be found blotchy, banded or singly colored. It is vary popular for carving and was used for weapons of the past.

Enhancements

Common enhancements to nephrite:

  • Fracture filling - wax - conceal cracks and fractures
  • Coatings - wax - to improve luster

Occurrence

Nephrite is found in Turkestan, Myanmar, Siberia (dark green rocks with black spots), Russia, China, New Zealand, Australia (black stones), USA, Canada, Mexico, Brazil, Taiwan, Zimbabwe (dark green), Italy, Poland, Germany and Switzerland. It has been carved by the Chinese for at least 2,000 years.

Sources consulted

  • Smithsonian Handbooks, Gemstones, Second Edition 2002

G&G Articles on Jade 1934-1980

The GIA has published all the G&G's from 1934 until 1980 online. The organization of the list by subject was done by Joseph Gill.