micROCKScopica - Symplectite in Granulite

Polarized light photomicrograph of a thin section of granulite from Manitoba, Canada.
The subject is an intricate "symplectic" intergrowth of pyroxene (pink and blue) and plagioclase (light gray) in a mafic granulite from N. Manitoba, Canada. The coherent distribution of colors, indicating optical continuity, shows that this pattern is actually provided by a few crystal of pyroxene and one of plagioclase intimately compenetrated. These minerals formed by replacement of a preexisting crystal of garnet. (Sample courtesy of Martha Growdon, Indiana University.)