Jade is an ornamental rock. The term
jade is applied to two different
metamorphic rocks that are made up of different
silicate minerals:
- Nephrite consists of a microcrystalline interlocking fibrous matrix of the calcium, magnesium-iron rich amphibole mineral series tremolite
(calcium-magnesium)-ferroactinolite (calcium-magnesium-iron). The
middle member of this series with an intermediate composition is called actinolite (the silky fibrous mineral form is one form of asbestos). The higher the iron content the greener the colour.
- Jadeite is a sodium- and aluminium-rich pyroxene. The gem form of the mineral is a microcrystalline interlocking crystal matrix.
Etymology
The English word
jade (alternative spelling "jaid") is derived (via French
l'ejade and Latin
ilia "flanks, kidney area")
[1] from the Spanish term
piedra de ijada (first recorded in 1565) or "loin stone", from its reputed efficacy in curing ailments of the
loins and
kidneys.
Nephrite is derived from
lapis nephriticus, the Latin version of the Spanish
piedra de ijada.
[2]
Overview
Nephrite and jadeite
Nephrite and jadeite were used from
prehistoric periods for
hardstone carving. Jadeite has about the same
hardness
as quartz. Nephrite is slightly softer, but is tougher (more resistant
to breakage) than jadeite. It was not until the 19th century that a
French mineralogist determined that "jade" was in fact two different
minerals.
[citation needed]
Among the earliest known jade artifacts excavated from prehistoric
sites are simple ornaments with bead, button, and tubular shapes.
[3] Additionally, jade was used for
adze heads,
knives, and other
weapons,
which can be delicately shaped. As metal-working technologies became
available, the beauty of jade made it valuable for ornaments and
decorative objects. Jadeite measures between 6.0 and 7.0
Mohs hardness,
and nephrite between 6.0 and 6.5, so it can be worked with quartz or
garnet sand, and polished with bamboo or even ground jade.
[citation needed]
Unusual varieties
Nephrite can be found in a creamy white form (known in China as
"mutton fat" jade) as well as in a variety of green colours, whereas
jadeite shows more colour variations, including blue, lavender-mauve,
pink, and emerald-green colours.
[citation needed]
Of the two, jadeite is rarer, documented in fewer than 12 places
worldwide. Translucent emerald-green jadeite is the most prized variety,
both historically and today. As "quetzal" jade, bright green jadeite
from
Guatemala was treasured by
Mesoamerican
cultures, and as "kingfisher" jade, vivid green rocks from Burma became
the preferred stone of post-1800 Chinese imperial scholars and rulers.
Burma (
Myanmar) and Guatemala are the principal sources of modern gem jadeite. In the area of
Mogaung in the
Myitkyina
District of Upper Burma, jadeite formed a layer in the dark-green
serpentine, and has been quarried and exported for well over a hundred
years.
[4] Canada provides the major share of modern lapidary nephrite. Nephrite jade was used mostly in pre-1800
China as well as in
New Zealand,
the Pacific Coast and Atlantic Coasts of North America, Neolithic
Europe, and Southeast Asia. In addition to Mesoamerica, jadeite was used
by Neolithic Japanese and European cultures.
History
Prehistoric and historic China
Main article:
Chinese jade
During
Neolithic times, the key known sources of nephrite jade in China for utilitarian and
ceremonial jade items were the now depleted deposits in the Ningshao area in the
Yangtze River Delta (
Liangzhu culture 3400–2250 BC) and in an area of the
Liaoning province and
Inner Mongolia (
Hongshan culture 4700–2200 BC).
[5]
Dushan Jade was being mined as early as 6000 BC. In the Yin Ruins of
the Shang Dynasty (1600 to 1050 BC) in Anyang, Dushan Jade ornaments
were unearthed in the tomb of the Shang kings. Jade was used to create
many utilitarian and ceremonial objects, from indoor decorative items to
jade burial suits. Jade was considered the "imperial gem". From the earliest
Chinese dynasties to the present, the jade deposits most in use were not only those of
Khotan in the Western Chinese province of
Xinjiang but other parts of China as well, such as Lantian,
Shaanxi. There, white and greenish nephrite jade is found in small quarries and as pebbles and boulders in the
rivers flowing from the
Kuen-Lun mountain range eastward into the
Takla-Makan desert area. The river jade collection is concentrated in the
Yarkand, the White Jades (
Yurungkash) and Black Jade (
Karakash) Rivers. From the
Kingdom of Khotan, on the southern leg of the
Silk Road,
yearly tribute payments consisting of the most precious white jade were
made to the Chinese Imperial court and there worked into
objets d'art by skilled artisans as jade had a status-value exceeding that of
gold or
silver.
Jade became a favourite material for the crafting of Chinese scholars'
objects, such as rests for calligraphy brushes, as well as the
mouthpieces of some
opium pipes, due to the belief that breathing through jade would bestow longevity upon smokers who used such a pipe.
[6]
Jadeite, with its bright emerald-green, pink, lavender,
orange and brown colours was imported from
Burma
to China only after about 1800. The vivid green variety became known as
Feicui (翡翠) or Kingfisher (feathers) Jade. It quickly became almost as
popular as nephrite and a favorite of Qing Dynasty's nouveau riche,
while scholars still had strong attachment to nephrite (white jade, or
Khotan), which they deemed to be the symbol of a nobleman.
In the history of the art of the Chinese empire, jade has had a special significance, comparable with that of gold and
diamonds in the West.
[7]
Jade was used for the finest objects and cult figures, and for grave
furnishings for high-ranking members of the imperial family.
[7]
Due to that significance and the rising middle class in China, today
the finest jade when found in nuggets of “mutton fat” jade — so-named
for its marbled white consistency — can fetch $3,000 an ounce, a tenfold
increase from a decade ago.
[8]
The Chinese character 玉
[9] is used to denote the several types of stone known in English as "jade" (e.g. 玉器, jadewares), such as
jadeite (硬玉, 'hard jade', another name for 翡翠) and
nephrite
(軟玉, 'soft jade'). But because of the value added culturally to jades
throughout Chinese history, the word has also come to refer more
generally to precious or ornamental stones,
[10]
and is very common in more symbolic usage as in phrases like 抛砖引玉 (lit.
'casting a brick (i.e. the speaker's own words) to draw a jade (i.e.
pearls of wisdom from the other party)'), 玉容 (a beautiful face; 'jade
countenance'), and 玉立 (slim and graceful; 'jade standing upright'). The
character has a similar range of meanings when appearing as a radical as
parts of other characters.
Prehistoric and historic India
The
Jainist temple of
Kolanpak in the
Nalgonda district,
Andhra Pradesh,
India is home to a 5-foot (1.5 m) high
sculpture of
Mahavira
that is carved entirely out of jade. It is the largest sculpture made
from a single jade rock in the world. India is also noted for its
craftsman tradition of using large amounts of green
serpentine or
false jade obtained primarily from Afghanistan in order to fashion jewellery and ornamental items such as sword hilts and dagger handles.
[4]
Prehistoric and early historic Korea
The use of jade and other greenstone was a long-term tradition in
Korea (c. 850 BC – AD 668). Jade is found in small numbers of
pit-houses and
burials. The craft production of small
comma-shaped and tubular "jades" using materials such as jade,
microcline,
jasper, etc., in southern Korea originates from the Middle
Mumun Pottery Period (c. 850–550 BC).
[11] Comma-shaped jades are found on some of the gold crowns of
Silla royalty (c. 300/400–668 AD) and sumptuous
elite burials of the
Korean Three Kingdoms. After the state of Silla united the Korean Peninsula in 668, the widespread popularisation of death rituals related to
Buddhism resulted in the decline of the use of jade in burials as prestige mortuary goods.
Southeast Asia
Archaeologists have discovered two forms of jade that can be found
across Taiwan through the Philippines, East Malaysia, central and
southern Vietnam, and even extend to eastern Cambodia and peninsular
Thailand. These two forms are called linling-o penannular earring with
three pointed circumferential projections and the double animal-headed
ear pendant. The forms are very similar in size and range from about
30-35mm in diameter. Furthermore, radiocarbon dates have dated these
forms in Southeast Asia from around 500 BC to 500 AD.
[12]
The electron probe microanalysis shows that the raw material of these
two kinds of jade artifact are nephrite jade originated from Taiwan,
named as the Fengtian nephrite. Evidence recovered from multiple sites
from Taiwan, the Philippines and the mainland southeast Asia suggests
that Taiwan is the main source of the exchange of this kind jade. During
the Iron Age of Southeast Asia, there might be skilled craftsmen
traveling from Taiwan to southeast Asia along the coastline of the South
China Sea, making jade ornaments for local inhabitants.
[13]
Māori
Nephrite jade in
New Zealand is known as
pounamu in the
Māori language (often called "greenstone" in
New Zealand English), and plays an important role in
Māori culture. It is considered a
taonga, or treasure, and therefore protected under the
Treaty of Waitangi, and the exploitation of it is restricted and closely monitored. It is found only in the
South Island of New Zealand, known as
Te Wai Pounamu in
Māori—"The [land of] Greenstone Water", or
Te Wahi Pounamu—"The Place of Greenstone".
Tools, weapons and ornaments were made of it; in particular
adzes, the '
mere' (short club), and the
Hei-tiki (neck pendant). These were believed to have their own
mana, handed down as valuable heirlooms, and often given as gifts to seal important agreements. Nephrite
jewellery of Maori design is widely popular with locals and tourists, although some of the jade used for these is now imported from
British Columbia and elsewhere.
[14]
Canada
Mesoamerica
Jadeite
Pectoral from the
Mayan Classic period (195 mm or 7.7 in high)
Jade was a rare and valued material in
pre-Columbian Mesoamerica. The only source from which the various
indigenous cultures, such as the
Olmec and
Maya, could obtain jade was located in the
Motagua River valley in
Guatemala. Jade was largely an
elite good, and was usually carved in various ways, whether serving as a medium upon which
hieroglyphs were inscribed, or shaped into
symbolic figurines. Generally, the material was highly symbolic, and it was often employed in the performance of
ideological practices and
rituals.
Enhancement
Jade may be enhanced (sometimes called "stabilized"). Note that some
merchants will refer to these as Grades, but it is important to bear in
mind that degree of enhancement is different from colour and texture
quality. In other words, Type A jadeite is not enhanced but can have
poor colour and texture. There are three main methods of enhancement,
sometimes referred to as the ABC Treatment System:
[15]
- Type A jadeite has not been treated in any way except surface waxing.
- Type B treatment involves exposing a promising but stained
piece of jadeite to chemical bleaches and/or acids and impregnating it
with a clear polymer resin. This results in a significant improvement of transparency and colour of the material. Currently, infrared spectroscopy is the most accurate test for the detection of polymer in jadeite.
- Type C jade has been artificially stained or dyed. The
effects are somewhat uncontrollable and may result in a dull brown. In
any case, translucency is usually lost.
- B+C jade is a combination of B and C: it has been both impregnated and artificially stained.
- Type D jade refers to a composite stone such as a doublet comprising a jade top with a plastic backing.
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