48 NEW YORK STATE MUSEUM 



pronounced. There are rather coarse masses of titaniferous magne- 

 tite, altering to leucoxene. This peculiar type of rock was noted in 

 the Elizabethtown quadrangle near New pond (Museum Bulletin 

 138, p. 43) and has also been observed just north of the edge of the 

 Mount Marcy quadrangle, on the east bank of the Ausable river above 

 Keene Center. The rock under pressure and shearing would readily 

 change into horneblende gneiss with parallel bands of feldspar and 

 horneblende. It is undoubtedly the parent rock of some puzzling 

 gneisses. Exposures have proved so limited that observations are 

 insufficient to prove whether it is a separate intrusive mass or a 

 peculiar phase of pyroxenic anorthosite. Its affinities are with the 

 anorthosites. 



