PLATE XXXIV. 



Fm. A. 



(Sp. No. 23746. Without analyzer, x 17.) 



Contact product of a granite. This muscovite-biotite-gueiss (?) is the result of contact action 

 of a granite upon a graywacke. Complete recrystallization of the sedimentary rock has taken place, 

 with the production of a porphyritic schistose structure. The large porphyritio muscovite plates 

 seen as white areas in the photomicrograph evidently represent the last products of recrystallization, 

 as they include all of the minerals which have been previously formed. They are possibly to be 

 looked upon as the product of mineralizers, to whose action may also be referred the presence of 

 tourmaline, which occurs in the section. The irregular white areas represent quartz and feldspar. 

 Dark greeuish-brown biotite is included in the muscovite, and with iron oxides occupies the areas 

 which in the figure are dark. (Described, p. 197.) 



Fig. B. 



(Sp. No. 23226. Without analyzer, xl7.) 



Photomicrograph showing the brecciated character of the matrix which is at times found between 

 the ellipsoids in the ellipsoidal basalts. In this specimen the schistose character is not so marked 

 as it is at times. 'Described, p. 117.) 



298 



