PLATE XXXVII. 



Fig. a. 



(Sp. No. 32958. Without analyzer, x 18.) 



Normal spilosite. Oval spots of macroscopical size, in which chlorite is the predominant con- 

 stituent, with some quartz, feldspar, rutile, and muscovite, are sharply defined from the surrounding 

 fine-grained groundmass, consisting of the same constituents, but with the muscovite in large quantity 

 and the chlorite very subordinate. (Described, p. 206.) 



Fig. B. 



(Sp. No. 32861. Without analyzer, x 38.) 



Spilosite in which the spots are of microscopical size and consist predominantly of chlorite 

 aggregates lying in the fine-grained quartz-albite groundmass. (Described, p. 207.) 



