The following is an extract from an article from the Orchid Archive:
Dr. Gubelein started the research on it with an article in Gems
and Gemology in the Winter of 1964. The green component is
definitely Ureyite, a clinopyroxene, and more or less Chromium
Jadeite, NaCrSi2O6. The mineral was perviously called Cosmochlor
(‘space’ + ‘green’), and was only known from meteorite samples.
I’m contacting meteorite dealers now to acquire a sample from the
It is thought by Dr. Gubelein and others that pure Ureyite is
actually a very dark green mineral, nearly showing black in
thick pieces. The reason Mawsitsit displays the lighter,
brilliant chrome green is that Ureyite has very finely mixed with
Albite, which is always found in both Jadeite and Mawsitsit.
It’s a low-temperature, high-pressure metamorphic rock, which is
why the banding and ‘flow’ are so nicely defined in Mawsitsit.
The material is extraordinarily variable - the tone and
proportion of light green, as well as the texture change from
rock to rock. There are also spots of pure metallic Chromite, and
rarely an iron-stained, red Albite vein running through it. In
addition, Chromium-containing sodic Amphiboles are found. The
closer you look at Mawsitsit, the stranger it becomes.
There is an excellent technical reference on the formation of
this rock. It was kindly supplied to me by Dr. E. Alan Jobbins
in the UK.
“Jadeite-Kosmochlor solid solution and chromian sodic amphiboles
in jadeites and associated rocks from Tawmaw (Burma)”
by Catherine Mevel and Jean-Robert Kienast, Laboratoire de
Petrologie Metamorphique, Universite P. et M. Curie, Paris It’s
They write “Sodic pyroxenes and amphiboles from jadeites and
amphiboles of the Tawmaw outcrop, Burma, contain the highest
chromium concentrations ever found in terrestrial rocks.”
Dr. E. Aspler
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