Definition
Mohs scale hardness 6 to 7
French mineralogist Alexis Damour didn't realize that what was once thought to be "jade" may actually be either nephrite or jadeite until 1863. Tremolite (calcium-magnesium)-ferroactinolite, a microcrystalline interlocking fibrous matrix of the calcium, magnesium, and iron rich amphibole mineral class, makes up nephrite (calcium-magnesium-iron). Actinolite is the series' middle component and has an intermediate composition (the silky fibrous mineral form is one form of asbestos). Green coloration increases with iron concentration. Actinolite is found in metamorphic greenschists/glaucophane schists, while tremolite is found in metamorphosed dolomitic limestones.
A pyroxene rich in sodium and aluminum is called jadeite. This is a microcrystalline interlocking growth of crystals and the most expensive variety of jade (not a fibrous matrix as nephrite is.) Only metamorphic rocks contain it.
From prehistoric times, nephrite and jadeite have both been utilized for hardstone carving. Jadeite and quartz both have a Mohs hardness of between 6.0 and 7.0, whereas nephrite has a little lower hardness of between 6.0 and 6.5, making it easier to work with quartz or garnet sand and polish with bamboo or even crushed jade. Nephrite, on the other hand, is more durable and breakage-resistant. Simple decorations with button, bead, and tube forms are some of the oldest known jade objects that have been discovered in ancient locations. Additionally, Jade is a beautifully sculptible material that has been used to make adze heads, blades, and other types of weaponry. Because of its beauty, jade has become valued for decorations and ornamental items as metalworking capabilities have advanced.
The Greek word for "kidney" is where the term Nephrite comes from. This is due to the notion that renal sickness might be cured in ancient times by wearing this particular type of jade around the waist.
While jadeite exhibits a wider range of colors, including blue, brown, red, black, dark green, lavender, and white, nephrite exhibits a creamy white form (referred to as "mutton fat" jade in China) as well as a variety of light green hues. The rarest of the two, jadeite has only been found in a total of 12 locations globally. Both historically and currently, transparent emerald-green jadeite is the most coveted kind. Bright green jadeite from Guatemala was prized by Mayan cultures under the name "quetzal" jade, while vivid green rocks from Burma under the name "kingfisher" jade became the favourite stone of post-1800 Chinese imperial intellectuals and monarchs. The main suppliers of contemporary gem jadeite are Guatemala and Burma (Myanmar). The dark-green serpentine in the Mogaung region of Upper Burma's Myitkyina District had a layer of jadeite, which has been extracted and traded for well over a century. Modern lapidary nephrite is mostly produced in Canada.
Origins
Only rocks that have undergone metamorphism and were created in recent or historic subduction zones include jadeite and nephrite. Rocks that originated under pressures greater than those that produced nephrite include jadeite. The majority of known jadeite deposits are located along or close to serpentinite faults. Instances of this type of deposit may be found in southern Europe, Russia, China, Taiwan, Guyana, New Zealand, Canada, and Burma. Nephrite is often found in marble from the Early to Middle Proterozoic period in Australia as lengthy lenses.
While there are no known jadeite deposits in Australia, the country is a significant global nephrite producer, mostly from the Cowell deposit. In Cowell, an area about the size of a major suburb has more than 100 occurrences. Nephrite, which weighs roughly 80,000 tonnes, was formerly present in these rocks. Nephrite has been shipped in large quantities from Cowell, primarily to Asia but also to Germany, Italy, the United States, Canada, and New Zealand.Nephrite jade has been mentioned in unsubstantiated accounts from Western Australia's Pilbara area. There are, however, mines of decorative stones sold as jade that are not genuine jades.