DEVELOPMENT OF EPIDOTE, CALCITE, AND HORNBLENDE 445 



linings of hornblende, and wrapped about with folia of micaceous gneiss. 

 These results are illustrated by figure 3. 



Calcite also is the constant companion of epidote; for example, at 

 East Ninety-eighth street, between Third and Fourth avenues (associated 

 with magnetite, scapolite, and perhaps wollastonite),West One hundred 

 and tenth street and Ninth avenue. West One hundred and ninetieth 

 street and Amsterdam avenue. The most interesting locality of such 

 association is still within observation on the north side of West One hun- 

 dred and thirty-fifth street, west of Amsterdam avenue. Here, in the 

 huge crumpled mass of black hornblende schist, the bright greenish 

 yellow seams, 2 to 5 centimeters in thickness, consist largely of epidote 



Figure Z. — Yellow Nodules of epidotic Hornblende Gneiss imbedded in Micaceous Gneiss. 



The black coating is secondary hornblende. Veinlets of albite and quartz are shown. Locality, 

 East Ninety-ninth street and Lexington avenue. 



intimately mixed with quartz and partly or wholly replacing both feld- 

 spar and the original hornblende. Calcite alternates in parallel seams 

 and thin lenses, sometimes 10 to 15 millimeters in thickness, often inter- 

 mixed at the margins with epidote, quartz, and black prisms of recrystal- 

 lized secondary hornblende. A large part of the schist is thus striped 

 on cross section by yellow bands of epidosite, white seams of calcite, 

 black layers of hornblende, and occasional granular bands of pegmatite • 

 the yellow bands amount to 20 or 30 per cent of the rock. The calcite 

 is evidently not original, but a secondar}^ product, whose base has been 

 dissociated from the calcareous minerals, plagioclase feldspar and horn- 

 blende, during epidotic alteration. 



LXII— Bull. Geol. Soc. Am., Vol. 14, 1902 



