I would like to start a little dialogue about the Burmese rock
called Mawsitsit. I’ve recently sent samples to the AIGS lab in
Bangkok to try to determine the composition and environment of
formation of this unusual and beautiful stone.
For those not familiar, it is an opaque rock, presumably
metamorphic, with fine, sharply defined, ‘flowing’ green and
black bands. There are sometimes small white areas, and
translucent veins running through it, which are albite. Besides
banding, however, there are rocks with only black dots on solid
green, others with botroidal, fibrous growth of light green into
clear albite or black. Other samples look like green permafrost
patterns on a very fine scale. I have even seen pieces with red
needles in the clear albite veins. It’s wild stuff! I used to
cut thin sections in my school days at the geology lab at CU
Boulder, and I’ve never seen a rock that grew like this. A thin
section would be incredible under the microscope.
The green mineral has been determined to be Ureyite. In the
clinopyroxene group, Ureyite was formerly known as Cosmochlor or
Kosmochlor, and was only found in meteorites. Mawsitsit forms
in Northern Burma, in the Jadeite producing areas. The
composition of Jadeite is NaAlSi2O6, and Ureyite is NaCrSi2O6.
Chromium replaces Aluminum; it is essentially Chromium Jadeite.
There are black metallic spots sometimes as well, and a laser
analysis performed last week on one such spot yielded a
The black mineral that mixes with the green areas is also the
mineral Ureyite, according to the analysis done so far. It is
thought that pure Ureyite is very dark green to black, but when
it mixed with albite, in this case, it got lighter and formed the
brilliant green color in Mawsitsit. I find this a little tough
to buy, but stranger things have happened in rocks I guess.
Any insight out there? Does anyone have any cosmic Cosmochlor
they’ll sell to me? Thank you.