Figure 14. Microprobe elemental maps of a brown fibrous alteration patch within a plagioclase porphyroclast in Sample 149-900A-83R-2, 60-65 cm. The photos have a long dimension of roughly 160 µm and increasing brightness marks increasing concentrations. A. The K concentrations occur in patches with irregular to fibrous shapes associated with a nonpleochroic fibrous amphibole. B. The concentration of Ca marks the unaltered surrounding porphyroclast. C. The Mg and Fe concentrations roughly coincide with the K concentration in the brown-stained alteration patch, except for one of the K-rich alteration fibers near the center of the photograph. D. The Al concentration coincides with Ca concentration in the unaltered surrounding plagioclase porphyroclast.