Nephrite
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.
- March-April 1934, Jadeite thought found in America (Oregon), p. 54, 1p.
- [http://www.gia.edu/research-resources/gems-gemology/back-issue-archive/May-June-1934.pdf">May-June 1934, Jade, p. 80, 3pp.</a>
- May-June 1934, Red Jade, by M. Ehrmann, p. 84, 1p.
- Fall 1944, Nephrite found in Lander, Wyo., in 1936, p. 170, 1p.
- Fall 1948, Jade Carving in China, p. 82, 5pp.
- Spring 1950, Jadeite and nephrite found in Calif., p. 289, 1p.
- Summer 1951, Jadeite and nephrite found in Calif., and artifacts, p. 76, 3pp.
- Spring 1952, Jade in Mexico, p. 147, 5pp.
- Summer 1954, The Nature of Jade, p. 38, 9pp.
- Fall 1956, Jadeite from San Benito County, Calif., p. 331, 4pp.
- Fall 1960, Jade Cutting Today, p. 81, 9pp.
- Winter 1964, "Pigeon eye" nephrite from Wyoming (shows chatoyant spots), p. 251, 2pp.
- Summer 1966, Taiwan jade (nephrite), p. 62, 1p.
- Spring 1976, Jade, China's Contribution to Fine Art, by A. Alexander, p. 145, 8pp.
- Fall 1979, Clarification of Composition of Maw Sit Sit, p. 217, 2p.
- Summer 1980, Australia Likely To Be Major Supplier of Jade, by J. Stone, p. 331, 1p.
- Summer 1943, So-called "Mexican jade" is calcite, p. 87, 1p.
- Winter 1955, Cat's-eye nephrite, p. 238, 1p.
- Spring 1958, Jadeite triplets, p. 134, 3pp.
- Winter 1961, Jadeite "Yunnan Jade" from Burma (showing absorption spectrum), p. 242, 2pp.
- Spring 1962, Rare gray-blue jadeite, p. 283, 1p.
- Winter 1963, Faded dyed jadeite, p. 100, 2pp.
- Summer 1964, Stable color in dyed jadeite, p. 181, 1p.
- Winter 1965, Dyed nephrite first seen at the GIA, p. 363, 2pp.
- Winter 1965, A new type of jadeite triplet (two pieces of jadeite, green coloring in center), p. 369, 2pp.
- Winter 1967, Dyed jadeite, p. 245, 1p.
- Summer 1969, Glass jade imitation, p. 58, 2pp.
- Winter 1970, Glass-like jade imitation, p. 249, 3pp.
- Summer 1971, Dyed lavender jadeite, p. 323, 2pp.
- Summer 1972, Jade substitute (glass), p. 44, 2pp.
- Summer 1972, Jade-like minerals, p. 50, 3pp.
- Fall 1972, Distinguishing burial jade from burned jade not yet possible, p. 83, 2pp.
- Fall 1972, Paraffin-treated jade, p. 84, 2pp.
- Fall 1972, Blue jade-like material (tremolite), p. 91, 2pp.
- Fall 1972, A cat's-eye yellow jadeite, p. 93, 1p.
- Winter 1972, Testing dyed antique replicas of jade, p. 112, 1p.
- Winter 1972, Jade cat's-eye (?), p. 113, 1p.
- Spring 1973, Jade imitations in devitrified fibrous glass (meta jade, Imori stone), p. 134, 2pp.
- Summer 1973, Durability of jadeite vs. nephrite, p. 175, 2pp.
- Fall 1973, Treated lavender jadeite, p. 214, 2pp.
- Fall 1974, Unevenly dyed jadeite, p. 350, 1p.
- Spring 1975, A "meta jade" glass with spectrum of natural jadeite, p. 27, 2pp.
- Fall 1975 Rare, nearly transparent, light gray faceted jadeite, p. 73, 2pp.