"Mawsitsit" is a polyminerallic material (a "rock") which has achieved some prominence as both a gemstone and a carving material. While some have called Mawsitsit a "jadeite", in reality the dominant mineral is another clinopyroxene, kosmochlor. It should not, therefore, be considered a variety of jadeite. It was first noted in the early 1960’s by the famed Swiss gemologist Eduard J. Gübelin during field investigations in Myanmar (“Burma”)

Mawsitsit was the result of high pressure, low temperature metamorphism of a chromium-rich ultramafic rock. It occurs on the rim of a peridotite intrusion that has been altered to serpentine. It is only found in Tawmaw, Myitkyina-Mogaung District, Kachin State, Myanmar;the occurrence in northern Myanmar appears to be unique. The locality is near the historic imperial jadeite mines of northern Myanmar.



Composition:

Mawsitsit is a rock composed of several different minerals; the proportions of each component mineral can vary from specimen to specimen. Most of the component minerals of mawsitsit contain chromium as either an essential element or as an impurity. They include:

● Kosmochlor – the dominant mineral species in mawsitsit is kosmochlor, a sodium chromium pyroxene previously called “ureyite”. (Ureyite was discredited as a mineral species when it was determined to be identical to kosmochlor.) Kosmochlor constitutes about 60 percent of mawsitsit, and is the primary component of both the brilliant emerald green and dark green-black patches.

● Chromian Jadeite – a chromium-enriched jadeite makes up approximately 15 percent of mawsitsit.

● Chromian Eckermannite – a chromium-enriched sodium, magnesium, iron amphibole group mineral, makes a small contribution of only about 4 percent of mawsitsit.

● Chromian Albite – a chromium-enriched albite usual constitutes 1 per cent of mawsitsit.

● “Symplectite” – On several occasions, derivative descriptions of the mineralogy of mawsitsit have included “symplektite” (symplectite) in the list of the mineral species present. Symplectite is not a mineral but rather a petrographic texture, a microscopically-fine intergrowth of two or more minerals resulting from high-pressure metamorphism.

● Minor and trace minerals include chromite (usually as opaque, microscopic relict grains), natrolite, an imprecisely identified chlorite-group mineral and a imprecisely identified serpentine-group mineral.

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Bibliography:

• Anthony, John W., Bideaux, Richard A., Bladh, Kenneth W., and Nichols, Monte C. (1990): Handbook of Mineralogy: Mineral Data Publishing, Tucson, Arizona

• Chiu Mei Ou Yang. 1984. A terrestrial source of ureyite. American Mineralogist, Vol. 69, pp 1180-1183

• Colombo, F., C. Rinaudo and C. Trossarelli. 2000. The mineralogical composition of maw-sit-sit from Myanmar. Journal of Gemmology. Vol. 27 No.2: pp 87-92

• Gübelin E.J. (1964–65) Maw-sit-sit: A new decorative gemstone from Burma. Gems & Gemology, Vol. 11, No. 8, pp. 227–238, 255

• Gübelin E.J. (1965b) Maw-sit-sit – A new decorative gemstone from Burma. Journal of Gemmology, Vol. 9, No. 10, pp. 329–344

• Gübelin E.J. (1965c) Maw-sit-sit proves to be jade-albite. Journal of Gemmology, Vol. 9, No. 11,
pp. 372–379

• Hänni H.A., Meyer J. (1997) Maw-sit-sit (kosmochlore jade): A metamorphic rock with a complex composition from Myanmar (Burma). Proceedings of the 26th International Gemmological Conference, Idar-Oberstein, Germany, pp. 22–24

• Htein, W. and A.M. Naing. 1994. Studies on kosmochlor, jadeite and associated minerals in jade of Myanmar. Journal of Gemmology. Vol. 24, pp.315-320

• Qi, L., X. Lu, W. Liu and Q.Ouyang. 2003. Maw-sit-sit jade from Burma: A particular jade formed by dynamic metamorphism and metasomatism. Journal of Gems and Gemmology. Vol. 5 No. 4, pp.1-7