Kosmochlor
A green sodium chromium pyroxene first found in an iron meteorite and later in Burmese jade.
Key facts
- Formula
- NaCrSi2O6
- Family
- Silicates
- Crystal system
- Monoclinic
- First described
- the Toluca iron meteorite, 1897
Kosmochlor was first described in 1897 from the Toluca iron meteorite of Mexico; its name means cosmic green. It was rediscovered in the Coahuila iron in 1965 and named ureyite, after the chemist Harold Urey, before the older name was restored. It was later found in jadeite rocks in Myanmar.
What it is
Kosmochlor is a pyroxene, a relative of jadeite in which chromium replaces aluminium. It is a deep emerald green.
Where it is found
In meteorites it occurs in graphite–troilite nodules of IAB irons such as Toluca and Canyon Diablo, often with krinovite and chromite, and in some chondrites. On Earth it is found in jade rocks from Myanmar, where it colours some green jade.
How it is recognised
Tiny bright green grains are visible in polished nodules under a microscope; analysis shows sodium, chromium and silicon.
Did you know?
Kosmochlor is one of the oldest named minerals first found in a meteorite.
Some deep green Burmese jade owes its colour to kosmochlor.