Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeite forms solid solutions with other pyroxene endmembers such as augite and diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr endmember). Pyroxenes rich in both the jadeite and augite endmembers are known as omphacite.A selection of antique, hand-crafted Chinese jadeite buttons
The name jadeite is derived (via French: l'ejade and Latin: ilia) from the Spanish phrase "piedra de ijada" which means "stone of the side". It was believed to cure kidney stones if it was rubbed against the side of the afflicted person's body. The Latin version of the name, lapis nephriticus, is the origin of the term nephrite, which is also a variety of jade.
Jadeite is formed in metamorphic rocks under high pressure and relatively low temperature conditions. Albite (NaAlSi3O8) is a common mineral of the Earth's crust, and it has a specific gravity of about 2.6, much less than that of jadeite. With increasing pressure, albite breaks down to form the high-pressure assemblage of jadeite plus quartz. Minerals associated with jadeite include: glaucophane, lawsonite, muscovite, aragonite, serpentine and quartz.
Rocks that consist almost entirely of jadeite are called jadeitite. In all well-documented occurrences, jadeitite appears to have formed from subduction zone fluids in association with serpentinite. Jadeitite is resistant to weathering, and boulders of jadeitite released from the serpentine-rich environments in which they formed are found in a variety of environments.
Jadeite's color commonly ranges from white through pale apple green to deep jade green but can also be blue-green (like the recently rediscovered "Olmec Blue" jade), pink, lavender and a multitude of other rare colors. Chloromelanite is a very dark green to black variety. Color is largely affected by the presence of trace elements such as chromium and iron. Its translucence can be anywhere from entirely solid through opaque to almost clear. Variations in color and translucence are often found even within a single specimen. Jadeite is reported from California, USA; Myanmar; New Zealand; Guatemala; other localities of jadeite include Kazakhstan; Russia; British Columbia, Canada; Alaska, USA;