Science Fair Project Encyclopedia
- Information about Thomas Biskup 's roguelike game can be found at JADE.
An ornamental stone, jade is a name applied to two different silicate minerals. Nephrite is a form of the amphibole actinolite (a mineral that also includes a form of asbestos). The second, the mineral jadeite, is a pyroxene. Nephrite has the formula Ca2(Mg, Fe)5Si8O22(OH)2. Jadeite has the formula NaAlSi2O6. The two are quite similar in appearance and it wasn't until 1863 that the two forms of this gemstone were distinguished.
It is an exceptionally tough material, and was first used for things such as axe heads, knives, and weapons. Later, as other materials could replace jade as a weapons material, it became appreciated for its beauty.
Nephrite can be found in a creamy white form as well as a green color, while jadeite shows more color variation. Of the two, jadeite is rarer, and is the form of jade mostly used in Central America. Nephrite jade was used mostly in China and New Zealand.
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 Yang Ze River delta (Liangzhu Jade culture 3400–2250 BC) and in an area of the Liaoning province in Inner Mongolia (Hongshan Culture 3500–2200 BC). From about the earliest Chinese Dynasties until present, the jade deposits in most use were from the region of Khotan in the Western Chinese province of Xinjiang. 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 northward into the Takla-Makan desert area. River jade collection was concentrated in the Yarkand , the White Jade (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 where made to the Chinese Imperial court and there transformed into objets d'art by skilled artisans as jade was considered more valuable than gold or silver.
In New Zealand, where it is known as greenstone or pounamu, nephrite was fashioned for centuries by Maori to make weapons and ornaments, and is still widely used to make carved jewellery although the mining of it is restricted and closely monitored.
- Laufer, Berthold. 1912. JADE: A Study in Chinese Archaeology & Religion. Reprint: Dover Publications, New York. 1974.
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