I.AWSON. ] 



Malignite. 



359 



Analysis of Amphibole- Malignite. 



Si( ) , 



A1,0 : , 



Fc,( ), 



Fe( ) 



CaO 



Mg< ) 



Na,C) 



K 2 



P 2 5 



Ti0 2 



H,( ) 



5I-38 

 15,88 

 1.48 



4-37 

 8.62 



443 

 7-57 

 4.20 



.98 



. 1 2 



•42 



Total 



99-45 



As compared with the garnet-pyrox^ne-malignite, the chief 

 features of interest in this analysis are that, while the silica and 

 total alkalies remain about the same in the two rocks, there is 

 a decrease in lime and ferric oxide in harmony with the absence of 

 melanite and an increase in ferrous oxide and soda in harmony 

 with the replacement of asgerine-augite by arfvedsonite. 



The interest attaching to the rocks described in the preceding 

 pages is twofold. To the systematist they furnish new material 

 for any detailed scheme of classification of rocks. To the student 

 of pedogenesis, to whom artificial schemes of classification are 

 liable to be a hindrance rather than a help, they afford another 

 instance of a very sharply-defined petrographic province in which 

 the different types of rock are undoubtedly the products of differ- 

 entiation from a common magma. As a problem in magma 

 differentiation the field evidence and the material collected are 

 unfortunately both two scant to permit of a satisfactory discussion. 

 A few closing observations upon the inter-relations of the three 

 types of malignite may, however, be offered. From the sketch 

 map, Fig. 1, it will be apparent that the most basic or nepheline 

 bearing type is quite subordinate in extent to the other two types 



CONCLUDING REMARKS. 



