You sent this message to all the net. I thought I would respond
anyway because we have seen similar textures. First, you may have anatase
instead of rutile, although we find anatase replacing sphene more often
than ilmenite. Second, we also find pseudorutile in ilmenite that one
may confuse with rutile or sphene. Third, we find many of our 10 kbar
granulites have rutile with some ilmenite lamellae, and the result is a
red rutile rather than the yellow droplets of pure rutile. In such rocks,
rutile included in quartz or feldspar is often pristine and can be
analyzed for minor Fe, Al, Cr, Nb, OH. Fourth, we find ilmenite with
rutile lamellae and patches in amphibolites, high level granites and
deep seated granulites. I think some rutile is produced by oxidation of
ilmenite to form hematite and rutile, or growth of late magnetite nearby.
It is tempting to think that rim rutile in granulites is prograde or
produced by isobaric cooling, but I think that this is a dangerous
assumption. We find that most ilmenite in granulites has reset Mg and Mn.
One of my students, Jodie Hayob, conducted experiments on
ilmenite-quartz-hypersthene-rutile and commented on some of these problems
in Contr. Min. Pet. in around 1993.
On Tue, 9 Oct 2001, PULAK SENGUPTA wrote:
> Dear Simon,
> Hope you are keeping fine! I need your advice to interpret an oxide
> intergrowths that I observe in enderbite. The intergrowth contains roughly
> 70-80% ilmenite and rest rutile. In places, rutile grains are found to move
> out of ilmenite boundary due to granular exsolution. The Fe2O3 content of
> ilmenite is low (<8mol%). I shall be thankful to you for your opinion on the
> pre-exsolution composition of this oxide intergrowth.
> With best personal regards,