/. The Rocks of Monte Ferru. 529 



Columbargiu rock (B) is in ornose with the symbol III. 5. (2) 3. 

 (4) 5. The Bonorva rock (C) has the symbol III. 6. 1(2). 4, 

 the name pilandose being assigned to this subrang.* The 

 symbols of these subrangs show clearly the highly sodic 

 character of these rocks, and support the view that the 

 supposed leucite is really analcite. 



The olivine and augite nodules in the Scano basalt are 

 described in the paper cited, and only their analyses need be 

 given here, for the sake of completeness. The analyses by 

 Doelter here, also, are clearly very faulty. 



ABC 



Si0 2 41-24 50-13 43-77 



Ti0 2 0-10 1-91 



A1 2 3 0-21 7-08 



Fe 2 3 _ 0'48 1-10 0-61 



0,0 3 .._ nil 



FeO__ 8-36 4-41 24-90 



MnO trace 0-05 



NiO __ 0-21 0-02 



MgO 49-90 13-73 29*21 



CaO nil 20-06 trace 



Na 2 1-88 



K 2 0-25 



HO 0-11 



100-62 100-73 98-49 



A. Olivine. Nodule in analcite basalt. Sp. gr. = 3-307 at 20°. 

 Scano. H. S. Washington analyst, op. cit., p. 746. 



B. Augite. Nodule in analcite basalt. Scano. H. S. Wash- 

 ington analyst, op. cit., p. 747. 



C. Olivine. Nodule in " leucite basalt. " Scano. C. Doelter 

 analyst, op. cit., p. 78. 



Geophysical Laboratory, 



Carnegie Institution of Washington, 

 Washington, D. C, January 26, 1915. 



*H. S. Washington, Jour. Geol., xxii, 751, 1914. 



