File:Lavender jadeitite (jadeite jade) (Hpakan-Tawmaw Jade Tract, Hpakan Ultramafic Body, Naga-Adaman Ophiolite, Late Jurassic, 147 Ma; alluvial clast (placer jade) (14925435180).jpg

Lavender jadeitite from the Jurassic of Burma. (field of view ~7.0 cm across)

“Jade” refers to more than one specific type of metamorphic rock. The four categories of “jade” are:

   1) jadeitite (jadeite jade)
   2) nephrite/nephritite (nephrite jade)
   3) chromian jade (maw sit sit)
   4) serpentine jade

Jadeitite (= jadeite jade) is a rare metamorphic rock composed of jadeite pyroxene (Na(Al,Fe)(Si2O6)). Published research on Burmese jade generally indicates that the jadeitite rock masses formed by metasomatism of albitites (= plagioclase feldspar metamorphites) at the periphery of serpentinized mantle peridotite bodies. The mantle peridotite was part of a subducting slab of Mesozoic-aged oceanic lithosphere that was emplaced upward and against southeast Asian continental lithosphere by obduction.

The rock shown above is lavender jadeitite, which is a scarce color variety. Whitish and near-white jadeite occurs throughout this rock,plus hints of pale-greenish gray jadeite near the lower left edge.

Composition: the lavender color of the jadeite clinopyroxene (Na(Al,Fe)(Si2O6)) in this rock appears to be the result of ferrous iron to ferric iron (Fe+2 → Fe+3) intervalence charge transfer (Rossman, 1974).

Geologic unit: Hpakan-Tawmaw Jade Tract, Hpakan Ultramafic Body, Naga-Adaman Ophiolite

Age: Syngenetic zircons indicate that Burmese jadeitite formed at 147 Ma (late Tithonian Stage, near-latest Jurassic. The serpentinite host rocks formed (metamorphic age) at 163 Ma (Middle Jurassic). Older literature interprets Burmese jadeitite as Tertiary in age, hosted by Late Creatceous to Eocene serpentinized peridotites.

Locality: alluvial clast (placer jade) from unrecorded locality (possibly in the vicinity of Phakant), upper reaches of the Uyu River (Uru River), western Kachin State, Indo-Burma Range, northern Burma

References on Burmese jade:

Bender, F. 1983. Geology of Burma. Berlin. Gebruder Borntraeger. 260 pp.

Hughes, R.W., O. Galibert, G. Bosshart, F. Ward, Oo T., M. Smith, Sun Tay Thye & G.E. Harlow. 2000. Burmese jade: the inscrutable gem. Gems & Gemology 36(1): 2-26.

Qiu Zhili, Wu Fuyuan, Yang Shufeng, Zhu Min, Sun Jinfeng & Yang Ping. 2008. Age and genesis of the Myanmar jadeite: constraints from U-Pb ages and Hf isotopes of zircon inclusions. Chinese Science Bulletin 54: 658-668.

Rossman, G.R. 1974. Lavender jade, the optical spectrum of Fe3+ and Fe2+ --> Fe3+ intervalence charge transfer in jadeite from Burma. American Mineralogist 59: 868-870.

Shi Guanghai, Cui Wenyuan, Cao Shumin, Jiang Neng, Jian Ping, Liu Dunyi, Miao Laicheng & Chu Bingbing. 2008. Ion microprobe zircon U-Pb age and geochemistry of the Myanmar jadeitite. Journal of the Geological Society of London 165: 221-234.

Shi Guanghai, Cui Wenyuan, Wang Changqiu & Zhang Wenhuai. 2000. The fluid inclusions in jadeitite from Pharkant area, Myanmar. Chinese Science Bulletin 45: 1896-1901.

Shi Guang-Hai, Jiang Neng, Liu Yan, Wang Xia, Zhang Zhi-Yu & Xu Yong-Jing. 2009. Zircon Hf isotope signature of the depleted mantle in the Myanmar jadeitite: implications for Mesozoic intra-oceanic subduction between the Eastern Indian Plate and the Burmese Platelet. Lithos 112: 342-350.

Shi Guanghai, Jiang Neng, Wang Yuwang, Zhao Xin, Wang Xia, Li Guowu, E. Ng & Cui Wenyuan. 2010. Ba minerals in clinopyroxene rocks from the Myanmar jadeitite area: implications for Ba recycling in subduction zones. European Journal of Mineralogy 22: 199-214.