Dear All,
I am currently working on a diamond exploration project where the only
indicator minerals (of kimberlite and lamproite) turning up in the
tropically-weathered soils are chromites - this is not so unusual because
the silicates often get toasted by the laterisation.
However, the chromites are extremely Zn rich (for chromite anyway) around
10% ZnO, with MgO <2%, and Cr2O3 51-55%. Has anyone else ever come across
this type of chromite? Is it likely to be mantle metasomatism? can there be
a crustal paragenesis?
More generally, has anyone any information on the replacement of Mg with Zn
in any other type of mineral, in a lithospheric mantle (or any other)
setting?
Thanks
Dr Kevin Leahy
Exploration Consultants Ltd
Henley-on-Thames
UK
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