Fig. 5. In this cathodoluminescent image myrmekite with quartz vermicules (black) has formed between two K-feldspar crystals (blue) or between K-feldspar and plagioclase (beige). In some places the cores are more sodic (pinkish) than in the more calcic plagioclase of the myrmekite. Large plagioclase crystal (upper left, beige) shows a fracture along which Ca has been removed to make a vein extending into the center of the crystal. The photomicrograph in the previous presentation, (Fig. 3) represents the final stage of replacement in this sequence where all altered plagioclase grains (with sodic cores or with cores and rims having the same An-content) have either been replaced by microcline or by recrystallized, albite-twinned, unzoned, sodic plagioclase An_12-15. One must be reminded that grains most strongly altered have been replaced by K-feldspar, and those plagioclase crystals less-altered still remain. Unfortunately, replacement processes destroy the evidence.