JADE (JADEITE, NEPHRITE) DEPOSITS

Jade is the gem name for mineral aggregates composed of either or both of two different minerals, Jadeite and Nephrite. Jadeite is a sodium-rich aluminous pyroxene; nephrite is a fine-grained, calcium-rich, magnesium, iron, aluminous amphibole. All jade is composed of fine-grained, highly intergrown, interlocking crystals of one or both of these minerals. Though neither mineral is very hard (6-7), jade is one of the toughest gem minerals known because of the intergrown nature of the individual crystals.

Most jade on the market is composed of nephrite; jadeite jade is quite rare and in its emerald-green, translucent form is referred to as Imperial Jade or "gem jade". A small amount of Cr in jadeite accounts for the color of imperial jade. Other color-based names for jadeite jade are Yunan Jade, for a uniquely appearing dark green, semitranslucent jade, Apple Jade for apple (yellowish green) green jade, and Moss-in-Snow for white jade with vivid green spots and streaks.

Nephrite and jadeite jade ranges in color from a somewhat greasy-appearing, white ("mutton fat jade") to dark and light shades of green, gray, blue-green, lavender, yellow, orange, brown, reddish-brown, and black. An important dark green variety of nephrite is sometimes known as "spinach jade". The chromophore in all nephrite jades is usually Fe. Nephrite jade is usually opaque to translucent in thinner pieces.

The name jade has been, and continues to be, applied to a variety of materials that superficially or closely resemble jade but are not composed of either jadeite or nephrite. Some of the problem can undoubtedly be traced to cultural and historical differences in word usage. In China, for example, the word jade has traditionally been applied not only to nephrite and jadeite jade, but to green serpentine and soapstone (talc) whose appearance closely resemble true jade. Common misnomers and the materials they represent are: "Korean" Jade for serpentine or gem serpentine (bowenite), "Indian" Jade for aventurine, "Mexican Jade" for green-dyed calcite, "Transvaal Jade" for green hydrogrossular garnet, "Amazon or Colorado Jade" for amazonite (blue-green or green) feldspar and "Oregon or Swiss Jade" for green chalcedony.

Jadeite is a mineral that is restricted in occurrence to certain metamorphic rocks that have undergone metamorphism at high pressures but relatively low temperatures. Jadeite jade is found exclusively as nodular or lens-shaped masses in serpentinite. Nephrite jade, which is also a product of metamorphism (and fluid infiltration), does not apparently require the very special P-T conditions of jadeite and is much more widespread. It is also found in association with serpentinite in all known localities. Because of its extreme toughness in contrast to the weaker material it forms in (serpentine), jade is nearly always found as weathered boulders and cobbles in stream deposits or glacial sediment.

Historically and presently important jade producing localities are:

Burma, near Tawmaw and Hpakon

Turkestan (central Asia between Iran and Siberia)

Canada, British Columbia Southern Frazier River drainage,

USA.,Wyoming, near Lander; since 1936 , Alaska, in Kobuk

River Watershed at Jade Mountain

New Zealand, South Island

Others: Poland (white nephrite); Taiwan; Monterey Co.,

California (poor quality jadeite); Guatemala (green

jadeite); Japan; U.S.S.R. (near Lake Baikal, green

nephrite).

While jadeite is mined today primarily in Myanmar, small quantities can be found in Guatemala. Although neolithic jadeite axes were found in Europe, it is not known where this prehistoric jadeite was mined, although it is possible that the material came from a deposit in the Alps.

Nephrite is mined in Canada, Australia, the United States, and Taiwan. http://www.highestoffer.com/jade.html

The Emerald Buddha, the sacred image that is enshrined at Wat Phra Kaeo in Bangkok, Thailand, was carved from a solid block of beautiful green jadeite.http://www.escati.com/emerald_buddha.htm

The ancient jade carved in China was what we today call nephrite jade: an amphibolite mineral. (Interestingly enough, the word nephrite comes from the Greek word for kidney, nephros, a bit more scholarly version of the same thing.) In the 19th Century , it was discovered that the material from the new world was not the same mineral as the jade from China. The mineral from Central America, a pyroxene, was called jadeite to distinguish it from the The Chinese knew about jadeite, travelers had brought back some jadeite from Burma as early as the thirteenth century. But China was turning inward at that time and this foreign Kingfisher Stone, as they called it, referring to the brightly colored feathers of the bird, was not considered to be real jade. It only became popular in the eighteenth and nineteenth century when trade with Burma opened up again.

http://www.highestoffer.com/jade.html

Although nephrite jade is China’s original “Stone of Heaven,” fine jadeite, as in this matched pair of semi-transparent bangles (53.4 mm in interior diameter, 9.8 mm thick), is the most sought-after of jades in the Chinese community today.

http://www.palagems.com/burma_jade.htm

Map of Upper Burma showing the jade mines in the far north. Maw-sit-sit is mined in the vicinity of Hpakan.

(Courtesy of Richard Hughes)

JADE AND MAW-SIT-SIT OF MYANMAR

JADEITE

variety Imperial JadeNa(Al,Fe)Si2O6

Tawmaw, Myanmar

Translucent bright green jadeite, called imperial jade, is among the most highly prized of all jades. Jade is an excellent material for carving because of its extreme toughness.

Size / Weight: 42x22x3 mm / 25.11 carats

http://www.nhm.org/research/minsci/

Portions of this article originally appeared in Gems & Gemology, Vol. 36, No. 1, pp. 2–26.

http://www.palagems.com/burma_jade.htm

A “cousin” to jade,- - maw sit sit is an attr

active ornamental s tone that is an inter

growth mainly of alb ite, clinochlore, kos

mochlor, chromian j adeite, and eckerma

nnitic amphibole. Th - - ese two maw sit sit

cabochons weigh 9 .8 7 ct (oval) and

ccc848

An uncut jade cobble of Burma.

Gemology

Maw-sit-sit may be distinguished from jadeite and nephrite by its appearance as well as its physical and optical properties. It has a refractive index that ranges from 1.52 (most common) to 1.74 (least common) depending on the aggregate mineral composition. The density is therefore also somewhat variable, falling between 2.5–3.5g/cm3. Most cutters agree that the hardness falls between 6 and 7 on the Mohs’ hardness scale. Rough and cut maw-sit-sit

Dr. Vince Manson, of the GIA, first suggested in 1979 (based on unpublished data) that maw-sit-sit might contain ureyite, which is a sodium chromium pyroxene (NaCrSi206) where chromium (Cr) replaces aluminum (Al) in the chemical composition. Ureyite, which was named in honor of Professor H.C. Urey, is today properly termed kosmochlore. The name kosmochlore (green from outer space) is derived from the fact that it was originally found only in meteorites. Dr. Henri Hanni, of the SSEF, in Basel Switzerland, noted in 1986 (based on unpublished data) that maw-sit-sit is composed of six main components. They are as follows: chromite, ureyite, chrome-jadeite, symplektite, chrome amphibole, and a matrix of lighter minerals.

MAW-SIT-SIT: Geology & mining

Maw-sit-sit is an aggregate of numerous minerals found in the famous jade mining region of Tawmaw in the Himalayan foothills of northwestern Burma. This small mining area lies approximately half a mile northwest of the village of Namshamaw. The maw-sit-sit mining area is found in part of what is known as the Namshamaw dike. Maw-sit-sit, like the jadeite found in this region was formed due to high pressure regional metamorphism. This region lies on a plateau at an elevation of approximately 3000 feet within the Uru river drainage basin.

Maw-sit-sit is a byproduct of jadeite mining and is quite rare in comparison to jade. The mining techniques used today are similar to those employed three decades ago when Dr. Gubelin first stumbled upon the unique gem material, with the exception of modern machinery used to excavate and tunnel through the thick overburden.Production has increased recently with demand, however, fine quality maw-sit-sit remains difficult to acquire.

There are actually two types of maw-sit-sit being found:

• Maw-sit-sit – the rich green hue with a medium tone containing contrasting black streaks or spots.

• Kyet Tayoe – the lighter apple green hue with a fainter tone containing little or no black streaks or spots.

Of the two, maw-sit-sit is certainly more attractive. Until demand increases, it will be difficult to determine the potential supply but thus far it seems to still be quite a rare occurrence.

Sketch m ap of Upp er Burma

, showing the route

to the jad e mines a t Hpakan.

Routes into Hpakan are virtually impassable during the rainy season.

At the Ka Htan West mine, located between Lonkin and Tawmaw, large peridotite boulders can be seen at the base of this 15-m-high wall of Uru Boulder Conglomerate.

In some areas at Tawmaw, miners must dig deep shafts through the overburden to reach the jadeite dikes. Dirt and gravel are removed by a rudimentary winch-and- bucket system.

Once a dike is exposed at Tawmaw, jackhammers are needed to break the jadeite apart.

- Mining of the Uru conglomerate is done in step like claims approximately 5 m wide that were originall

yseparatedbyt hi n “wal l s.”

At Mamon andc cc -cccc cc cccc

icular, miners ta ke advantage of the seasons wh

en the river is hi gh to dive for ja de. While a man

on land or a raft works the crude

air pump (which resembles four

bicycle pumps s trapped togethe

r), this diver at- Maw sisa search

es the river bott om for jade with the hose betwe

en his teeth (inset).

At Nansibon, backhoes are used to work the serpentinite boulder conglomerate in which jadeite boulders occur in narrow horizontal concentrations.

Thousands of wor k er s r emove t he di

rt and gravel at Hpakangyi t o r each

the Uru Conglomerate anditspromiseoffi ne j ade

ite. Using the most rudimentary of carr

ying devices – two crudely fashioned bamboo buckets – t

his young miner le ads a trail of labore

rs up the steep pat h from the bottom of the pit to a truck

that will carry the waste to the river.

The color of luck Miner with jade at the Uru River tailings dump in the center of Hpakan.

Top centre: Thisj adei t e boul der shows t he r ecccccccc cccc cccc ccc ccccccccccc cccc ccccc c

hat is usually associated with “ river jade .” Al though from the outside this appears to be a normal jadeite boulder, oxidants that entere

d through cracks on the surface have produ ced a large area of discoloration. Bottom lef

t: Note the thick yellow “mist ” around the ja deite in this boulder of “ mountain jade .” Rig

ht: A key advantage to jadeite taken from in situ deposits is that the quality of the materi

al is readily apparent.

The color of moneyExamining jadeite in Hpakan.

Leaving Las Vegas

A roomwith a view

U Tin Ngwe , who we nt from taxi driver t

o jade kingpin almo st overnight, stands

atop a small fortune of jade at his Hpaka

n home.

In Mandalay, cutters still use a board coated with a mixture of carborundum (of various grits) and hard wax to shape cabochons. They then polish jadeite on bamboo lathes, often without any abrasive

The Golden Hand

To get a better idea of the quality of color in this boulder, the dealer places a metal plate at the far side of a small area with potential and then uses a penlight to illuminate it..

“Windows” cut into this otherwise undistinguished boulder from the Burma Jade Tract reveal the presence of a rich green in the jadeite beneath the skin. Boulders such as this are the source of the fine green, orange-red, and lavender cabochons that are much sought-after in China and elsewhere.

In sawing jadeite boulders, center saw cuts (left) run the risk of cutting through a valuable area. A better method (right) involves making shallow saw cuts from one end (perhaps the thickness of a bangle, so that each slice can be used for bangles/cabs) until one hits good color. Then the process is repeated from the opposite end, again until good color is encountered. This defines the region of top-grade material. The process is repeated until the area of best color is isolated. These cross-sections also illustrate a show point and an oxidation stain penetrating the jadeite through a crack.

Vendors work t he morning jad

ei t e mar ket i n Mandalay .

Foreign buyers examine rough jadeite at the 1 9 9 2 ge m emporium at Rangoon ’s Inya Lake Hotel. Such emporiu ms were once the only legal way to do business in Burma, but today trading is possible via licensed private gem deal

ers.