part 8] 



METAMOKPHISM IN THE MOJfA COMPLEX. 



335 



epidote. It is, therefore, certain that, before the eruption of this 

 ancient volcanic series, the Penmynydd anamorphism of the Mona 

 Complex was complete. 



Fig. 1. — Fragment of mica-schist in an agglomerate of the 

 Bangor Volcanic Series. X 19. 



II. The Gwna Beds. 



New Analyses of the Quartzite. 



At the time of the issue of the Geological Survey Memoir, only 

 one analysis of a Gwna quartzite was available. Owing to the 

 kindness of Mr. W. B. Hartley, of the United Silica Company, I 

 am now able to communicate four analyses of the quartzite of 

 Graig-wen in Gynfor; while Mr. F. Russell, of the General 

 Refractories' Companj^ has kindly supplied one of that at 

 Llansrefni : — 



Si0 2 



I. 



II. 



III. 



IV. 



V. 



VI. 



95-98 



0-75 

 063 

 033 



1-20 

 0-84 



0-36 



94-11 



270 



0-20 

 0-34 

 0-23 

 092 

 0-50 

 0-64 

 0-50 



94-53 



2 V 61 



0-27 

 036 

 0-02 

 064 

 0-58 

 0-23 

 0-54 



96-80 

 0-16 

 1-74 

 0-40 

 0-04 

 0-03 

 0-48 

 0-24 



6 ; 36 



97-88 

 0-05 

 0-92 

 0-23 

 0-12 

 0-08 

 0-26 



0-38 



9586 

 04 

 1-75 

 0-35 

 0-24 

 0-07 



I 1-13 



•17 

 0-43 



Ti0 2 



A]o6;j 



Fe 2 O s 



CaO 



MgO 



K 2 



NaoO 



S0 3 



Loss over 109° 



Totals 



100-09 



100-14 



99-78 



10025 



99-92 



100-04 







i 









