A metamorphic rock with a complex composition from Myanmar (Burma) Authors: Henry A. Hanni & J. Meyer, Basel, Switzerland.Maw Sit Sit is a rock, composed from at least six different minerals as main constituents. Those can vary greatly in their relatives amounts and therefore the rock may vary strongly in its visual aspect as well as in its specific gravity value.
The name Maw Sit Sit is given by the local people and reminds the locality of origin near Kansi and Namshawa, N-Burma (Myanmar). Previously used names in the west were Jade-Albite or Chloromelanite.
The main constituents of Kosmochlor Jade are:
Chromite; small black relictic grains of metallic luster, mostly as cores in black Kosmochlor aggregates, provided they show central grains of higher luster.
Kosmochlor; forming nests of fine felty NaCrSi2O6 which are the typical black spots in some Maw Sit Sit. Kosmochlor is the Cr-Analogon of Jadeite NaAlCrSi2O6. The former name of Kosmochlor was Ureyite. Refractive index = 1.766/1.781, SG=3.6
Chrome-Jadeite; is encountered as larger single crystals forming blocky mosaics. There is a solid solution or mixed series situation between Jadeite, Chrome-Jadeite and Kosmochlor by the substitution of Al by Cr. In Maw Sit Sit, usually various members of this series are present.
Symplektite; is a vary fine mineral mixture which cannot be resolved microscopically. Symplekite is also green due to the chromium content of its components.
Chrome-Amphibole; or Amphibole, in larger crystals, depending on its chromium contents green or grey. After their chemical composition they were identified as Eckermanite bzw.
Arfvedsonite; Matrix is a mixture of bright mineral components (Zeolite, Chlorite, Albite, Serpentine) which fills the space between the minerals named above. Fine veinlets mainly also consist of Zeolite, Chlorite, Albite or Serpentine.
Maw Sit Sit was formed in connection with a high pressure low temperature rock metamorphosis which affected an ultrabasic body locally. New formations of minerals also took place after the culmination of the metamorphosis. Essentially it was a metasomatic reaction between serpentinites and albite dykes. The chromium which is found in most of the constituent minerals most probably stems from former chromite layers which have been dissolved during the metamorphic transitions. Remnants of chromite are sometimes found as relicts within the Kosmochlor spots. The Maw Sit Sit deposit is placed at the rim of a larger peridotite body which has been altered and serpentinized. The deposit is northern and close to the classical Jadeite location in Burma ( Tawmaw, Namshawa).
Colors of Maw Sit Sit : light green to black, monochrome, mottled or spotted, frequently with black spots or white spots and veinlets.
Density: 2.5-3.2 g / cm3 depending on composition
Refractive index: weak reading at approximately 1.52
Remarks regarding other names currently applied to the material (synonyms)
Maw-Sit-Sit is the name of a locality, and also the local name for the described rock in Myanmar (Burma).
Chloromelanite is an older mineral name of a pyroxene mineral which is not part of Maw Sit Sit. It might also be in use due to its descriptive name for” CHLOROS=GREEN” and “MELANOS=BLACK”.
Jade-Albite is a name composed of two mineral names which may occur in Maw Sit Sit, but are subordinate and less frequent so that it is not justified to use them for naming the stone.
Research carried out by H.A.Hanni & Jurg Meyer in 1984