Fig. 10. In this photomicrograph, the thin section of a granite in the Sierra Nevada is turned so that the microcline is at extinction (black) in order to show "ghost myrmekite." Albite-twinned plagioclase (tan to light gray and white, upper right side) has an extinction position that is optically parallel to extinction positions of islands of incompletely replaced plagioclase containing tiny quartz blebs (white) which occur scattered to the left of the plagioclase crystal in the microcline and to the far left in the microcline. When the thin section is rotated so the microcline grid-twinning becomes visible, these islands become invisible or nearly so, whereas the large plagioclase crystal is still distinct. The inclined, elongate, rounded grain (left side, center) in microcline is myrmekitic.