Tonalite from Belgium (La Helle). Thin section.

One of the few Belgian magmatic rock (probably the best known): the meta tonalite taken along the river "La Helle".

The picture below  shows clear crystals of quartz surrounded by plagioclase and biotite. The plagioclases are highly altered into fine grained mica and the biotite is partly transformed to chlorite.

      Plane polarized view.