THE DIFFERENCE BETWEEN
NEPHRITE & JADEITE
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NEPHRITE
In Chinese, the word Yü translated to English means precious stone and is used for the English word JADE. Yü is viewed by the Chinese as the true jade and comes in two forms; Nephrite and Jadeite.
Nephrite, is a silicate of calcium and magnesium of the amphibole group. It is a mineral that has a very hard and fibrous crystalline Structure. It is less hard than Jadeite, and when polished it has a soft oil-like appearance. Nephrite was the primary jade used in ancient China until about 1780 when large deposits of Jadeite were discovered in Burma (Miramar). Technically, Nephrite is not classified as a mineral, but a variety of the actinolite-tremolite series. The white-gray nephrite are usually closer to tremolite in composition while the green – yellow – brown are closer to actinolite. Chemical composition is usually listed as Ca2(Mg, Fe)5(OH)2(Si4O11)2. The fibers of actinolite and tremolite must be interlocking for the stone to be called Nephrite because the interlocking feature imparts the mineral’s toughness.
Therefore, the term “carved” is not correct when describing the working and shaping of objects made from Nephrite jades. The term “abrasives” is actually correct, because abrasive tools and grit are used to shape and form Nephrite Jade objects. What makes for value are those old standards of commerce; supply and demand. There are abundant supplies of Nephrite throughout the world, but the quality of Nephrite varies in color and translucency, qualities that determine value (Spinach green and Imperial white). Color and translucence of Nephrite have more to do with value because of the sheer abundance of nephrite off colors ( light spotted greens and pea greens).
General Actinolite (Nephrite) Information
Chemical Formula:
Ca2(Mg,Fe++)5Si8O22(OH)2
Composition:
Molecular Weight = 875.45 gm
Calcium 9.16 % Ca 12.81 % CaO
Magnesium 8.33 % Mg 13.81 % MgO
Iron 12.76 % Fe 16.41 % FeO
Silicon 25.66 % Si 54.91 % SiO2
Hydrogen 0.23 % H 2.06 % H2O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
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JADEITE
Jadeite is a silicate of sodium and aluminum within the pyroxene group. It is a mineral with an interlocking granular structure that can take on a very high-gloss, glass-like finish. Both Nephrite and Jadeite are colorless or white when free of foreign elements. The pale white jade was the color most valued by the ancient Chinese (mutton fat to denote purity). However, due mainly to the presence of compounds of iron, chromium, and manganese, both gemstones exhibit a range of colors that surpass a rainbow. Often, the original colors of ancient jades have been affected by exposures with chemicals (cinnabar and Iron oxide burial practice) in the earth or other organic substances. Nephrite has a wide range of browns, grays and greens that rarely occur in jadeite. The color range for Jadeite is also very diverse in sheds of color and translucency. Jadeite was not worked extensively in China prior to the eighteenth century. Thus, most jade artifacts created before the latter part of Qing Dynasty (1644-1911) are fashioned of Nephrite Jade. Jadeite is an extremely scarce gemstone whose popularity has soared in the last 200 years. Basically, Jadeite comes from one of several sources; Miramar (Burma), Guatemala, California, Japan and Switzerland. The fine color highly translucent Jadeite is only available from Miramar (Burma) and Central America. The fine Jadeite is rare and highly sought after by the Chinese and other collectors of fine gems.
General Jadeite Information
Chemical Formula:
Na(Al,Fe+++)Si2O6
Composition:
Molecular Weight = 205.03 gm
Sodium 11.21 % Na 15.11 % Na2O
Aluminum 11.84 % Al 22.38 % Al2O3
Iron 2.72 % Fe 3.89 % Fe2O3
Silicon 27.40 % Si 58.61 % SiO2
Oxygen 46.82 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Ian (Fung Gen Qua)
Ancient Chinese Jade Specialist for over 33 years