656 



CROSS, ID DINGS, PIRSSON, WASHINGTON 

 TABLE III. 



NORDMARKOSE (lITCHFIELDITe), LITCHFIELD, ME. 

 Bull. 168, U. S. Geol. Surv., p. 21. 



1.006 — (0.300 + O.OIO + 0.01C 

 6x + o.y = 680 (SiO„) 

 x + y = 136 (Na 2 0) 

 x = 102 



y = 34 



In the rock the extra A1 2 3 enters mica, combining with the 

 olivine and magnetite molecules and because of low magnesia 

 making lepidomelane. 



FORMULA. 

 K2O.AI.O3.6SiO- 



NaoO.AUO3.6SiO;, 



Ca0.AKO 3 .2SiO„ 

 NaoO.Al 2 3 .2Si6„ 

 A1 2 3 . 



Fe0.Fe„0 3 - 

 2MgO.SiO„ 

 2FeO.SiO," - 



CLASS I. 



Sal _ 9S-35 \ 7 



Fcm 3.81-1 



Persalane. 



ORDER 5. 



F _ 82.64 ^ 7 



L _ 9.66^1 



Canadare. 



H„0 = 



RANG I. 



K 2 Q'+Na„Q' _ i8( 

 CaO " 3 



No rdm arkase. 



>l 



K„0' 



Sal 95.35 

 Fern 3.81 



Na 2 0' I36^5"7 

 Nordmarkose. 



