PLATE VIII. 



A. Fine grained white gneiss (Vermont formation). Hoosac mountain. Microphotograph. Pol- 

 arized lifrht, x 33. 



Porphyritic feldspar twin (a) containing inclusions of quartz and mica which are arranged 

 parallel to the minerals of the groundmass outside. 



B. Albite schist (Hoosac schist). Hoosac mountain. Microphotograph. x 33. 



The large crystals of albite (a) contain inclusions of muscovite, chlorite, magnetite, and quartz. 

 The gentle curving of the mica of the groundmass between these feldspars is well shown. 



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