Fig. 24. Enlargement of the upper portion of Fig. 23, showing relationships of bordering grains. In the upper right center, microcline (grid-twinning) can be seen to penetrate the plagioclase (tannish gray) along fractures at the edge of the crystal so that the microcline narrows to two points (above and left of the white quartz grains). The lower pointed wedge of microcline then extends farther into the plagioclase in a thin line. In a similar fashion, the adjacent plagioclase also narrows to two points, each projecting in the opposite direction into the microcline.