THULEAN BASALTS 



783 



1 



Si0 2 48.79 



ALO a 11.96 



Fe 2 3 2.51 



FeO 12.10 



MgO 5.60 



CaO 10.15 



Na 2 2,40 



K 2 0.70 



H 2 0+ 0.40 



H 2 0— 0.65 



C0 2 0.41 



Ti0 2 4.17 



P 2 5 0.37 



S 0.06 



Cr 2 3 trace 



V 2 3 0.11 



MnO 0.21 





Table V 











Analyses of Iceland 



Basalts 









2 



3 



4 



5 



6 



7 



8 



47.27 



48.06 



47.67 



53.39 



49.67 



46.97 



49.04 



14.44 



12.14 



15.81 



13.37 



13.57 



13.87 



13.54 



0.97 



4.89 



1.70 



2.07 



7.79 



8.27 



2.43 



10.15 



9.04 



10.41 



10.62 



7.21 



5.76 



10.46 



10.30 



9.80 



8.08 



3.30 



5.53 



4.76 



7.42 



11.73 



12.28 



12.23 



6.90 



12.37 



14.46 



10.55 



1.86 



2.07 



1.98 



3.84 



1.57 



1.75 



2.43 



0.18 



0.31 



0.27 



1.19 



1.20 



0.45 



0.53 



0.33 



0.10 



0.21 



1.37 



0.15 



n.d. 



0.48 



0.09 



0.04 



0.10 



0.08 



.... 



n.d. 



0.19 



none 



none 



none 



none 



n.d. 



n. d. 



none 



2.36 



1.55 



2.17 



2.28 



1.50 



1.99 



2.51 



0.12 



0.07 



0.10 



1.24 



n. d. 



n. d. 



0.38 



none 



0.01 



n.d. 



n. d. 



n.d. 



n.d. 



.... 



0.04 



none 



n. d. 



n. d. 



n.d. 



n. d. 



• • . • 



0.07 



n.d. 



n.d. 



n. d. 



n. d. 



n.d. 



• . . . 



0.19 



0.17 



0.16 



0.20 



n.d. 



1.20 



0.20 



100. 12 t 



100.48$ 



100.89 



99.85 



100.56 



99.48 



100.26 



1. Basalt (Tertiary). Holmatindur, Eski-fjord ; Harwood, analyst. Holmes, 



Mineralogical Magazine, volume 18, 1918, page 193. 



2. Olivine basalt (Quaternary). Grunda-f jord ; Harwood, analyst. Holmes, 



Mineralogical Magazine, volume 18, 1918, page 196. 



3. Basalt (pre-Glacial). Reykjavik; Washington, analyst. 



4. Basalt (post-Glacial) . Allamannagja, near Thingvellir ; Washington, analyst. 



5. Basalt (Recent). Near Naefurholt, Mount Hecla; Washington, analyst. 



6. Basalt (Recent). Hecla. Rosenbusch, Elem. Gest, 1910, page 399. 



7. Basalt (Recent?). Randholar Volcano; Hauser, analyst. Komorowicz, 



Vulk. Stud. Ins. Atlant, 1912, page 25. 



8. Basalt. Iceland. Mean of numbers 1, 2, 3, 4, and 5. 



With the exception of Wright's specimen of the Hecla basalt, which is 

 notably higher in silica, alkalies, and phosphorus, but lower in mag- 

 nesia and lime, these basalts much resemble each other. There are a few 

 points of difference, such as the different iron oxides of number 3 and 

 the lower magnesia of number 1, but the first four are alike in showing 

 rather high iron oxides, with ferrous oxide preponderant over ferric — 

 strikingly so except in number 3. The other characters call for no special 

 comment here, being much like those of the basalts previously studied. 



* Includes CI, trace ; NiO, trace ; BaO, trace ; SrO, none. 

 f Includes CI, 0.01 ; NiO, 0.01 ; BaO, none ; SrO, none. 

 t Includes Zr0 2 , none ; BaO, none. 



