Nephrite jade from Oregon, USA.
"Jade" refers to certain rare metamorphic rocks, some of which are high-quality enough to be gemstones. The three types of jade are: 1) jadeitite, or jadeite jade; 2) nephrite/nephritite, or nephrite jade; and 3) chromian jade, or maw sit sit. Green serpentinites and green grossularites are sometimes nicknamed "jade", but they are not jade.
Jadeitite (= jadeite jade) is a crystalline-textured metamorphic rock composed of jadeite pyroxene (Na(Al,Fe)(Si2O6)). The most famous occurrene is in Burma, southeastern Asia.
Nephrite jade (nephritite) is a crystalline-textured to felted-textured metamorphic rock principally composed of one or more amphibole minerals (tremolite to actinolite, Ca2Mg5Si8O22(OH)2 to Ca2(Mg,Fe)5Si8O22(OH)2).
Mawsitsit (chromian jade) is a very rare, polymineralic metamorphic rock only known from Burma. Reported minerals include kosmochlor pyroxene, chromian jadeite pyroxene, chromite, chromiferous arfvedsonite amphibole, symplectite, thompsonite zeolite, albite feldspar, and serpentine.
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Jade info. from signage at the University of Wyoming Geological Museum (Laramie, Wyoming, USA):
"Jade is an ornamental stone found in many parts of the world. Jade consists of two minerals, nephrite and jadeite. Nephrite is a vareity of the amphibole mineral actinolite: Ca2(Mg,Fe)5Si8O22(OH)2. Jadeite on the other hand is a type of pyroxene and forms monoclinic crystals. Jadeite's chemical formula is Na(Al,Fe+3)Si2O6."
"The word "jade" is derived from the Spanish term piedra de ijada (first recorded in 1565), or "flank stone", because it had a reputed efficacy in curing ailments of the loins and kidneys. Nephrite gets its name from Latin "lapis nephriticus", meaning "kidney stone" because it was often worn to remedy diseases of the kidneys."
"Jade is about as hard as quartz, quite tough, beautifully colored, and can easily be shaped. Both nephrite and jadeite were used during the Stone and Bronze Age and in the ancient dynasties of China."
"Nephrite is the most common form of the two varieties, being found in a creamy white form as well as various green hues. The green color is the result of iron within the crystal lattice. When iron is not present, the mineral is colorless to cloudy white. Jadeite, on the other hand, shows more color variations, including blue, lavender, pink, and green. Jadeite is found in fewer than 12 documented productive places around the world. The translucent emerald-green jadeite is the most valued variety, both now and historically. Places like Guatemala and Burma are principal locations for jadeite. Canada is the main producer of lapidary nephrite. Jade is the official gemstone of British Columbia, where it is found in the Lillooet, Liard, and Omenica Mining Divisions. Nephrite jade was used mostly in pre-1800 China as well as New Zealand, the Atlantic and Pacific Coasts of North America, Neolithic Europe, and Southeast Asia. Jadeite was used by Neolithic Japanese and European cultures."
"Nephrite jade is found in several places in the United States, including the states of Alaska, California, Connecticut, Georgia, Nebraska, Nevada, Oregon, Pennsylvania, Washington, and Wyoming. Jadeite on the other hand is found in California, North Carolina, Oklahoma, South Dakota, and Washington."
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Locality: unrecorded / undisclosed, but attributed to Oregon, USA
