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REGINALD A. DALY 



peculiarities. A study of the chemical and mineralogical analyses 

 showed that it must be rich in FeO and relatively poor in MgO. 

 The magnetite and ilmenite are abundant in the ground-mass. 



Mr. Steiger's analysis of the rock gave the proportions shown 

 in Table II. 



TABLE II 



1 Ultra-femic olivine basalt, lava flow of 1852. 

 la Molecular proportions in 1. 



Using the Rosiwal method, checked by the analyses, the Mode 

 (weight percentages) was calculated to be: 



Olivine 32.0 



Augite 27.0 



Labradorite 35.7 



Ilmenite 2.5 



Magnetite 2.5 



Apatite .3 



Assuming the probable values of the specific gravity for each 

 mineral, the specific gravity of the rock was calculated to be 3 . 16, 

 which agrees satisfactorily with the actual value, 3.065, found by 

 the proper weighing of coarse powder of the rock. 



In the Norm classification the rock enters the hitherto unnamed 



