The term Jade (alternative spelling "jaid" is derived (via French l'ejade and Latin ilia) from the Spanish term piedra de jiadaI (first recorded in 1565)) is applied to two different metamorphic rocks that are made up of different silicate materials:
JADEITE comes in a wide range of attractive colours; many shades of green, yellow and reddish orange, plus white, grey, black, brown and lavender. The colouration is often streaked or mottled, giving jadeite gemstones an interesting visual texture that carvers can use to create imaginative and intriguing effects. Jadeite was also known as "loin stone" from its reputed efficacy in curing ailments of the loins and kidneys.
NEPHRITE is also accepted as jade in the international gem and jewellery industry. It ranges from translucent to opaque and can be light to dark green, yellow, brown, black, grey or white. Its colours tend to me more muted than jadeites but they're also often mottled or streaked. Nephrite is derived from lapis nephriticus, the Latin version of the Spanishpiedra de ijada.
Modern gemologists use the word "jade" as a generic term for both nephrite and jadeite. Nephrite and jadeite were used from prehistoric periods for hardstone carving. Jadeite has about the same hardness as quartz (between 6.0 and 7.0 on the Mohs scale) while nephrite is slightly softer.
It was not until the 19th century that a French mineralogist determined that "jade" was in fact two different minerals. Among the earliest known jade artefacts excavated from the prehistoric sites are simple ornaments with bead, button and tubular shapes.
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. Over 100 axe heads made from jadeite quarried in northern Italy in the Neolithic era have been found across the British Isles. However, because of the difficulty of working this material, all the axe heads of this type found are thought to have been non-utilitarian and to have represented some form of currency or be the products of gift exchange.
Jadeite from the Motagua Valley, Guatemala, was used by the Olmec and Maya people as well as the indigenous people of Costa Rica. Typically the most highly valued colours of jadeite are the most intensely green, translucent varieties, though traditionally white has been considered the most valuable of the jades by the Chinese, known for their carefully crafted jade pieces.
Jadeite is reported from California, Myanmar, New Zealand, and Guatemala. Other localities include Kazakhstan, Russia, British Colombia, Canada, Alaska, Italy, and Turkestan.
Canada is the principal source of modern lapidary nephrite. Nephrite jade was used mostly in pre-1800 China as well as in New Zealand, the Pacific Coast and the Atlantic Coasts of North America, Neolithic Europe and Southeast Asia.
Nephrite jade in New Zealand is known as pounamu in the Māori language and is highly valued, playing an important role in the Māori culture. It is considered as taonga or treasure.