Fig. 13b. A scanning-electron photomicrograph that shows celsian islands (ce, white) in altered plagioclase partly replaced by K-feldspar (magnification: 8,000x). Image is from same area as in Fig. 13a. The holes are bordered by concentrations of K (lighter gray, incipient K-feldspar, kf). In some places the celsian occurs on hole walls adjacent to the K concentrations.