786 H. S. WASHINGTON DECCAN SALTS AND PLATEAU BASALTS 



the rock appears to be very fresh. No nephelite could be detected. The 

 section of the specimen examined by me differs from one from Thorshavn 

 described and figured by Holmes, in that the latter shows much more 

 ilmenite-magnetite and seems to be free from glass. According to 

 Holmes, the aphyric specimen from Waags-f jord is much like the other, 

 except that microphenocrysts of labradorite replace the megaphenocrysts 

 of the Thorshavn rock, and augite ("enstatite-augite") is somewhat more 

 abundant. Crystals of "ilmenite" are very abundant, and this mineral 

 seems to have been among the last to crystallize out. 



An analysis by me of the porphyritic Thorshavn basalt and one by 

 Harwood of the aphyric Waags-f jord rock are given in Table VII, with 

 the average of the two. The two analyses are much alike as regards many 

 of the constituents, but the porphyritic lava is lower in silica, ferrous 

 oxide, and titanium, but higher in alumina and soda. The differences 

 correspond with its porphyritic and more feldspathic character and the 

 less calcic composition of the plagioclase. 



Table VII 



Analyses of Faroe Basalts 



12 3 



Si0 2 47. 5S 49.70 48.64 



A1 2 3 17.12 10.98 14.05 



Fe 2 3 3.03 3.02 3.03 



FeO 8.73 11.19 9.96 



MgO 5.18 5.34 5.26 



CaO 10.12 9.71 9.92 



Na 2 3.89 2.22 3.06 



K 2 0.86 0.63 0.75 



H 2 0+ 0.13 0.96 0.55 



H 2 0— 0.06 0.92 0.49 



Ti0 2 2.72 4.83 3.78 



P 2 5 0.41 0.33 0.38 



CI n. d. 0.02 



S ' n. d. 0.05 



V 2 O a n. d. 0.03 



MnO 0.14 0.22 0.18 



99.97 100.18* 100.05 



1. Basalt, porphyritic. Thorshavn, Stroruoe ; Washington, analyst. 



2. Basalt, aphyric. Waags-f jord, Suderoe ; Harwood, analyst. Holmes, Geo- 



logical Magazine, 1918, page 201. 



3. Basalt, Faroe Islands. Average of above. 



* Includes Cr,0 3 , trace ; NiO, none ; BaO, 0.01 ; SrO, none. 



