Kyanite zone (Sample 114)

The assemblage is Ky + Bt + Ms + Pl + Qtz.
The rock is a coarse-grained kyanite-biotite schist. The kyanite here shows its characteristic high relief, low order interference colours (up to yellow), cleavage and simple twins. The AFM diagram at right shows the bulk composition plotting in a two-phase Ky-Bt field, and suggests that staurolite might still be stable in more Fe-rich rocks under the same conditions.

Field of view is 6 mm wide.