HOOSAC MOUNTAIN 



65 



of the feldspar is here in broad simple twins, but part is microeline in simi- 

 lar crystals. The feldspar of this rock needs further investigation. 



The tine-grained silvery green or green schists (Rowe schists) which 

 occupy a strip < »n the extreme eastern b< >rder of the map, overlying the albite- 

 schist (Hoosac), have not been microscopically investigated by the writer. 



AMPHIBOLITES. 



Last to be described are heavy dark rocks, generally fine grained, in 

 which the eye recognizes dark crystalloids of hornblende and irregular 



Fig L't -Amphibolite. Mount Holly, Vermont. 



A band of amphibolite - feet wide, interstratined with gneiss ;iuil i rumpled with it iu a large duuble fold. The 

 Structure of the amphibolite coincides iu every detail with that of the gneiss. 



patches of feldspar and cubes of pyrite. In the finer grained varieties the 

 rock has a glistening surface due to plates of biotite in tihns mixed with the 

 hornblende, and the rock then lias a somewhat schistose structure. They 

 rocks have been found in several localities, in all but one case in beds par- 

 allel to the structure of the inclosing gneisses and contorted with them. 



These rocks occur abundantly in the Green mountains. The most 

 remarkable occurrence is peidiaps near Mount Holly and Wallingford, Vt, 



