Fig. 6. Microcline (dark gray, grid-twinning) in this photomicrograph from myrmekite-bearing granite is in a more advanced stage of replacement of plagioclase. Plagioclase (light tan) in the center and upper left has been completely replaced by K-feldspar (lower right). Note that the albite twinning of the grid-twinning in the microcline is parallel to the albite twinning in the plagioclase.