BiO, 



39 13 



Norm. 





Mode. 



A1 2 3 



3 48 



Olivine 



72-14 



Olivine 54-80 



Pe.O, 



1-83 



Enstatite 



1602 



Enstatite 1931 



FeO 



7-58 





i 3-48 



Picotite 5-16 



MgO 



42-15 



Magnetite 



2-60 



Magnetite 2-60 



CaO 



•07 



Ilmenite 



•30 



Carbonates 5 99 



H 2 0- 



2-80 



Chromite 



■30 



Serpentine 9 94 



H 2 + 



•80 



Water 





Silica -96 



co„ 



3 05 



Co 2 



305 



Water 1'58 



Ti0 2 



16 









Cr 2 3 







100-77 



100-34 



Ni(,V,(. 



•01 









MnO 



•21 









100-75 



Calculating the position of this rock in the American 

 Classification we find it falls in V 1. 4 1. 1.; and for this 

 rang and sub-rang the names Dundase and Dundose are 

 suggested. These seem peculiarly appropriate as indi- 

 cating both the locality of this rock and its affinity with 

 the neighbouring rang and sub-rang Dnnase and Dunose, 

 the less aluminous olivine rock. The mode of the rock was 

 calculated on the following assumptions : — 



1. Magnesia and ferrous oxide enter olivine, enstatite, 



picotite and carbonates always in the proportion in 

 which they occur in the bulk analysis. 



2. Titanic oxide plays the part of silica in the olivine 



molecule. 



3. The rock was originally without ferric oxide. The 



magnetite therefore is an index of the amount of olivine 

 that has been converted into serpentine. 



4. The olivine was the only mineral attacked by the carbonic 



acid. 



5. The excess of the silica set free by carbonation of olivine 



over that absorbed in serpentinisation remains in rock 

 as quartz, chalcedony or opal. 

 It is probable that none of these assumptions is entirely 

 true, No. 3 especially is unlikely, for the picotite may con- 



