Jadeite

Jadeite is a pyroxene mineral with composition NaAlSi₂O₆. Jadeite is found only in metamorphic rocks that form under high pressure and relatively low temperature conditions, usually along transverse faults. It has a Mohs hardness of about 6.5 to 7.0 depending on the mineral impurities present. Associated minerals include: glaucophane, lawsonite, muscovite, aragonite, serpentine, and quartz. Jadeite's color commonly ranges from white through pale apple green to deep jade'' green but can also be blue-green (like the famous and recently rediscovered "Olmec Blue" jade), lavender, and a multitude of other rare colors. Color is largely affected by the presence of trace elements such as chromium and iron. It's 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. Currently, the best known sources of gem quality jadeite are California, Myanmar, New Zealand and more recently Guatemala; however, mineral jadeite is also found in California, British Columbia, Alaska, Turkestan, and a few other places.
Jadeite is one of the minerals recognized as the gemstone jade. The other is the green amphibole, nephrite. Typically, the most highly valued colors 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. Currently, the most highly valued variety of jadeite is known as "Imperial Green" jade and is characterized by an emerald green color with a high level of translucence. Other colors, like "Olmec Blue" jade, which is characterized by its deep blue-green, translucent hue with white flecking, are also becoming more highly valued because of its unique beauty and historical use by the Mesoamerican Olmec; however, this variety was only recently rediscovered and is only being minimally exploited by native Guatemalans. It is thus difficult to obtain and as yet too rare and little known to have attained great value as a gemstone. When purchasing jade, quality is determined by the degree of translucence, cleanness of color, and purity of color. Occasionally, other minerals like serpentine or quartz are sold as jade but the difference can be determined by cleavage and hardness.