PLATE XXII. 
Fig. a. — Altered spherulite in an aporhyolite. Specimen 280. Slide 280 D. Peach 
Orchard, southwest flank of Pine Mountain. In ordinary light, X 5. In polarized 
light the slide shows an even-grained quartz-feldspar mosaic, with the micropoiki- 
litic structure and with no trace of spherulitic crystallization. 
Fig. b. — An unaltered spherulite in an aporhyolite. Specimen 279. Slide G. H. W. 
(unnumbered). Raccoon Creek, Franklin County. In ordinary light, X 30. Ground- 
mass devitrified, but spherulitic crystallization still in a large part preserved. 
110 
