1921] 



NATURAL SCIENCES OF PHILADELPHIA 



181 



Spi^ f 



S Kiloau;Ua.*> 



CoiUooriiutErvHl 20icet. 



Fig. 10. — Albitite and plumasite occurrences of the Chester quadrangle, Delaware 

 County, Penna. A, Albitite occurrences; Co, abandoned corundum mines in 

 plumasite. 



