Gemological & Geological Research Old & New
Nephrite and Jadeite
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Gemological & Geological Research
Siberian Jade Slab
In this category we most certainly invite all Professional and Amateur Gemologists, Geologists, Institutional Participants and Mine Owners to share any pertinent research, whether old, new or theoretical in nature for the discussion of Nephrite Jade or Jadeite.
Translated to English from Chinese the word Yu ( pronounced ‘Ya’ ) is interpreted as meaning ‘Precious Stone’ which the English language terms as JADE.
Yu is considered by the Chinese as true jade which is recognized as two different minerals: nephrite and jadeite.
Nephrite, from the amphibole group, is a silicate of calcium and magnesium.
A mineral with a tough and fibrous crystalline structure less hard than Jadeite. When polished it has a soft oil-like appearance. Nephrite was the predominant jade carved in ancient China until large deposits of Jadeite were discovered in Burma (Miramar) about 1780. Technically, Nephrite cannot be classified as a mineral. Rather it’s a tightly felted composition of long needle like actinolite-tremolite crystals. White-gray nephrites are often closer to tremolite in composition while the green – yellow – brown tend more toward actinolite. Chemical composition is usually listed as Ca2(Mg, Fe)5(OH)2(Si4O11)2. The needle-like fibers of actinolite and tremolite have to be interlocking for the stone to be Nephrite because this felted structure imparts the incredible toughness nephrite is known for.
“Carved” is not entirely accurate when describing the forming of art pieces from Nephrite jade. The term grinding or abrasion is more correct, because abrasive tools and grit are used to shape and form Nephrite Jade Sculptures. 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 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
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 several sources; Miramar (Burma), Guatemala, California, Japan and Switzerland. The fine color highly translucent Jadeite is only available from Miramar (Burma) and Central America. 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
I’m going to take some heat for this but I’m convinced…..Contrary to popular belief
There is no jadeite found in the Eel River
Information on false Jadeite from Northern California Eel River
3.4 specific gravity same as jadeite
1.66 refractive index same as jadeite
6.5 hardness same as jadeite
These are the tests prospectors use to identify stones. None of these tests will help us in this case.
These stones from the Eel River that have been identified as Jadeite (for many years) are absolutely misidentified. All of the test we used said these stones were jadeite.They have the same specific gravity, refractive index and hardness. But they are not jadeite. After being given the test results from many samples with “jadeite specs” not one piece has ever tested as jadeite. I am now of the opinion that no jadeite exists in the Eel River. The true identity of this stone is a rare pyroxene rich diopside. It acts like jadeite in many ways. It can affix chromium. It contains lots of pyroxene. It is dense. It is hard. It takes a great polish. But now that the results are officially internet published first here on Timelessjade we all now know the truth. The stone labeled California jadeite in the San Francisco Museum of Natural History is most likely misidentified. By the way George Harlow (Curator American Museum of Natural History) is the authority who has actually verified this using the most sophisticated modern laboratory testing methods and machines that are far out of price range for the prospector.
Here’s a question. Does anyone out there know what crystal structure or chemical composition causes some jades that technically test out as nephrite to have a brittle, “glassy” texture? Some of the jades I’m thinking of are the currently available Cowell black from Australia, some California black jade, and some Wyoming material including the “Game Warden” jade. At this point all I know is that when I see it I don’t like it.
Hey Peter,
Not being a certified gemologist I can not site the chemical structure on the the jades that you mention here. However, under the microscope not all jades, or jadeite’s, are not created equal and that is for certain. Also, to answer your question I would believe multiple tests would have to be run on the same stone in multiple sites and in minuscule amounts. The Cowell Black, from 1972, that Donn Salt gave to me is more like the Wyoming Edwards Black, and those close to it, in that the fibrous nature of the nephrite is extremely tightly bound together with little to no chatoyancy. Yet the piece of Wyoming emerald green slab I just received from Sue Rees looks much more like the White and Black River jades of old Chinese fame. Very hard but not nearly as tightly felted as one would find in the early Cowell or the Edwards. It is my personal belief that as much as science would try to ‘pigeon hole” nephrite and jadeite, they will not be. Each bit of stone seems to have certain features common to that stone, and of course similarities exist. I think perhaps some of the problem, from the carving aspect, is more due to the types of tools used now and the types of tools used thousands of years ago. Long ago the drill speeds were not as quick and while being slower to work the stones were much less forgiving in the chipping and fracturing of different material. Like high speed polishing and slow hand polishing with the same grits should be different on different jades. Some jades after polishing look to me like old wood with the softer parts eaten away more and the harder ridges sticking up a bit. Take the famous Lake Tai Variegated nephrite for an extreme. It looks under microscopic conditions to be plates of actinolite and tremolite just jammed together and the Liangzhu, Dawenkou, and Hongshan Cultures of Neolithic China could work the material just fine. I have yet to hear much good news about California Black but have not had a chance for a look-see through my scope.
I’ve got great news about California black jade. After receiving the lab’s stone analysis and satisfying my need to know that this was indeed black nephrite we decided to do a test run. We just finished the run of beads and they are absolutely fantastic. Jet black with an incredible polish. I’ll send some rough to Antiquities, Plus for you to scope out and give us the comparison results. Thanks for providing this forum as it is a fantastic learning experience.