Fig. 7. In this photo of a road-cut exposure, a mafic facies of the Josephine Mountain pluton can be seen in the San Gabriel Mountains, north of Pasadena, California (USA). In the center of the photo several narrow bands (0.5 to 4 cm wide) of pink granite extend up-slope parallel to each other. If these narrow bands were pure quartz, most geologists would probably agree that the quartz was not deposited there by a magma consisting of 100% silica. The viscosity would be too great. Instead, most geologists would agree that the silica in the quartz vein was brought in by hydrous fluids and deposited there. The pink granite is not 100% silica but is at least 72%, and, therefore, it also would be unlikely to be injected as magma in such narrow channels (0.5 cm wide). These pink bands consist predominantly of microcline, quartz, myrmekite, and albite. On the basis of the myrmekite and other replacement textures, I interpret these narrow bands to be formed by K-metasomatism where hydrous fluids moved through parallel cataclastic shear zones.