PLATE XXXVIII. 

 Fig. a. 



(Sp. No. 32826. Without analyzer, x 38.) 



Photomicrograph illustrating the passage of spilosite to a desmosite. In the upper portion, 

 especially in the upper left-hand corner, of the figure, chlorite aggregates similar to those illustrated 

 in fig. B, PI. XXXVII, are seen. These become united, and thus there is a passage into the banded 

 product. This banded character is well shown in the lower half of the photomicrograph. (Described, 

 p. 207.) 



Fig. B. 



( Sp. No. 23755. Without analyzer, x 90. ) 



Occurrence and alteration of brouzite in bronzite-norite. This illustration shows the way in 

 which the bronzite occurs in the bronzite-norite. It is frequently included in the hornblende. The 

 bronzite alters around the edges and along the cracks to a yellowish-green fibrous serpentine mineral, 

 which is represented in the section by the dark fibrous material nest to the unaltered bronzite. This 

 secondary mineral then alters to a scaly aggregate of talc. These two secondary products can be 

 seen bordering the bronzite, especially well where it is traversed by a crack. (Described, p. 238.) 



306 



