378 DE. C. CALLAWAY ON THE METAMORPHISM OF [Aug. 1 898, 



aggregates similar to those just noticed. Mixed up with the chlorite 

 aud other interstitial matter, there is a fair proportion of quartz in 

 very small angular fragments. It can hardly be doubted that the 

 minutely granular aggregates consist of small fragments of quartz 

 and a little felspar, which have coalesced under the influence of 

 heat and pressure ; while the angular particles embedded in the 

 matrix are original fragments which have been kept asunder, and 

 protected by their soft environment. The pressure to which this 

 rock has been subjected has been comparatively slight. 



No. 449. — This slide also is very quartzose, and the other con- 

 stituents are similar, except that a little white mica is present, and 



Pig. 1.— Schist from Pant-y-Glo {No. U9). 



[A.lteration partial; quartz-fragments conspicuous, some of them tailing cjfi' 

 into mosaic. The minute quartz is often coalescent, Wliite mica (not 

 fragmental) is present in small proportion.] 



there is less epidote. This rock has been compressed to a moderate 

 degree, so that a distinct schistosity is produced, and this is strongly 

 accentuated by the mica. Many of the larger quartz-fragments are 

 still quite sharp and angular, lying for the most part with their 

 longer axes parallel to the foliation ; but some of them have appa- 

 rently been converted into granular mosaic. A few of them tail off 

 in one direction into mosaic, as if the thinner end of the fragment 

 had yielded to the heat, while the main part of it had resisted. 

 Minute particles of quartz surrounded by matrix are still angular. 



