Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Shea Dangelo
"Jade" is a term used for one of the many wonders produced by the natural processes of the earth. It is a very durable, and often beautiful gemstone that has been fashioned into tools, sculptures, jewelry, gemstones, and other objects for many millennia.
Jadeite and Nephrite: What’s
When one hears the term
“jade”, they often think of the brilliant hues of green that have made the gem
famous, but “jade” is actually composed of two categories: nephrite and
jadeite. These two categories contain a range of colors from the various shades
of white to dark green, sometimes gray, pink, lilac, red, blue, yellow, orange,
or black of the rarer and somewhat tougher jadeite, to the mid to dark green or
grey-green, white, yellowish or reddish of nephrite.
Jadeite and nephrite are both
regarded in China as 'zhen yu' (translated as 'genuine jade'). They may bear a
considerable resemblance to each other in terms of their appearance, their
hardness and the properties they exhibit when being processed. And, both are
tough, since they consist of dense, close-grained, matted aggregates. The ways
they differ from one another is in their chemical composition and colors.
Nephrite is a magnesium-rich amphibole whose chemical composition is Ca2(Mg,
Fe)5Si8O22(OH)2, and jadeite is an aluminum-rich pyroxene whose chemical
composition is NaAlSi2O6. Master Chinese craftsmen who worked with jade daily
recognized that some of the jade obtained was harder, denser, worked easier, and
produced a higher luster upon polishing (jadeite). This allowed them to make a
distinction between jadeite and nephrite long before scientists differentiated
the two in the 19th century.
As for color, as was stated,
each category of jade carries its own color range. In both, only in the very
finest jade is the color evenly distributed, though the “flaws” often found in
both jadeite and nephrite may not always be regarded as so. On the contrary,
veins, blemishes and streaks running through them create patterns that may be
considered particularly valuable to some.
Uses Throughout the Ages:
Originally admired for its
toughness (on Mohs Scale of hardness it ranges from 5 to 7 depending on its
composition), it was used mainly for tools and weapons in many cultures.
"Toughness" is the ability of a material to resist fracturing when subjected to
stress. "Hardness" is the ability of a material to resist abrasion. Early
toolmakers took advantage of these properties of jade and formed it into cutting
tools and weapons. It was used to make axes, projectile points, knives,
scrapers, and other sharp objects for cutting.
Later, because of the color
and translucence of some of the pieces found, the jade began to be cut, shaped,
and polished for other purposes such as jewelry, ornaments, statues, and
In ancient China, jade was
referred to as 'yu' (translated as the 'royal gem'). Nephrite was the first jade
uncovered in ancient China, and was the traditional jade used and carved, so
much so that the deposits of it are now but depleted in China. In the 14th
century, jadeite coming from Burma began to be traded to China on a wide scale.
The harder, denser, and easier worked composition of the jadeite became
preferred by Chinese artisans and the Chinese people, and is now the main type
of jade being traded in present day China. Similar to the way royals of
European countries wore precious gems such as rubies and diamonds as symbols of
status, jade became the symbol of status, power, purity, spirituality, and
health for China. The most wealthy and influential members of Chinese society
would even be buried in jade suits. In today’s society, jade in China sells for
about the same price per carat as diamond in the United States.
reverence for jade in China is unmatched, other cultures such as the Mayas,
Aztecs and Olmecs of Central America also honored and esteemed jade more highly
than gold, as is the sentiment toward jade in China. The Aztecs carried jade
figures of gods to whom they worshipped or carved masks and ornaments that would
be used in such rituals.
Along with other earlier cultures, New Zealand's Maoris began carving weapons
and cult instruments from native jade in early times, a tradition which has
continued to the present day. In other regions and cultures, such as ancient
Egypt, jade was admired as the stone of love, inner peace, harmony, balance,
wisdom, and was said to provide luck and protection for those that kept it in
The infatuation with this gemstone through the ages is a testament to man’s admiration of the beauty that the earth supplies through its natural processes. A beautiful rock to some and a sacred stone to others, jade will continue to capture the hearts of humankind, whether aesthetically or spiritually, for years to come.