The term jade refers to a number of tough fine-grained rocks used for carving as ornaments and implements. The various types of jade and jade-like materials are composed largely of one of these minerals: amphibole, pyroxene, epidote or serpentine. This guide discussed the various types of Chinese jade.
The Chinese use a term, translated as jade, for any beautiful rock or mineral thus, in addition to what we would call jade, they speak of Hanbai jade and snow jade (both white limstone ore marble) and Donglin jade (clear quartz). Today in the west the term jade is, at least by mineralogists, used only for rocks consisting mainly of either pyroxene or amphibole. Both pyroxene and amphibole are chain silicates containg aluminium and magnesium plus varying ammounts of calcium. iron and other elements. They differ, however, in their atomic structure.
There are two other types of material that warrant being called jade. One is composed mainly of the mineral serpentine and the other of the mineral aggregate known as saussurite (which includes epidote). My justification for this is that:
It would be hard for anyone without specialised equipment to distiguish beetween the four types.
The value of a jade object should be related to the artistry of its treatment, its physical appearance and also the hardness and toughness of the material rathger than to its mineralogy.
Amphibole jade (nephrite)
Amphibole jade is found in China and has been used there from the earlies times. It is usually somewhat softer than pyroxene jade but is still classified as a hardstone so it is confusing to use the Chines name, soft jade. When polished it often has a glassy lustre. Varieties include:
Hetian jade: From Hetian, Xinjiang Autonomous region. A classic jade varying considerably in colour. White is highly favoured and expensive.
Hemo jade: Mainly from Liaoning. Honshan culture jade and Liangzhu cultural jade are both mainly Hemo jade.
Pyroxene jade (jadeite)
Pyroxene jade is mainly found in Myamar and has only been used in China since about 1650. It is slightly harder (Mohs hardness of 7) than amphibole jade and when polished sometimes shows an attractive silky lustre. Because of its rareity it is often more valuable that amphibole jade. Imperial jade is a translucent brilliant-green variety coloured by traces of chromium that can be extremely valuable.
Serpentine jade is composed mainly of the mineral serpentine. The harder varieties are often mistaken for amphibole jade. Varieties include:
Xiu jade: from Xiuyan, Liaoning Province. It has a Mohs hardness of 2.5 to 5.5 and is usually white or light green. It is one of the classic Chinese jades.
New jade: a pale green transparent variety that had entered the market quite recently.
Saussurite jade ius composed of the mineral aggragate saussurite which is a fine grained mixture of feldspar and epidote. Its properties are very similar to those af amphibloe jade. One variety is:
Nanyang jade also known as Dushan jade: Comes from Nanyang, Henan Province and has a Mohs hardness of 6 to 6.5. Jiuquan jadfe from Gansu and Xinyi jade from Guangdong seem to be similar.
Most varieties of jade can be, and often are, "improved" by staining and other treatments.
Some materials that have been incorrectly sold as jade include:
Soapstone: A very soft rock composed maily of the sheet silicate mineral, talc. It is often mottled brown.
Inkstone: Various fine-grained sedimentarty rocks often dark grey or black.
Moss agate: Finely-crystallised quarts containing mossy areas of green chlorite. t is as hard as, or harder than, pyroxene jade but quite brittle.