L'aWson.] 



Malignite 



361 





Garnet-pyroxene- 



Araphlbole 



Difference 





malignite. 



malignite. 





oil ) , 



51.88 



5 1 -3 8 



-I" .50 



a 1 n 



1 4- 1 3 



I 5.00 



— 1.75 



Fe 2 3 1 





5.65 



4-1 £A 



~ 1 • 5 4 



Fe( ) 1 



/■39 



CaO 



10. Si 



8.62 



+2. 19 



MgO 



3-44 



4-43 



-- .99 







20 7 ' 57 1 =1 





K.,0 



4/57 r n 



9 4-20 1 



X7/ + -37 1 



TiO, 



• j j 



. 1 2 



'+ .21 



P. 2 5 



.96 



.98 



— .02 



H,0 



.18 



•42 



- .24 



Total 



1 00.4 1 



99-45 





Sp. g. 



2.888' 







Yet with these closely-allied chemical characteristics there are, 

 as already pointed out, important mineralogical differences, the 

 first rock containing an abundance of melanite and the second 

 none; the first having much ;egerine-augite and no amphibole, and 

 the second much soda-amphibole and but a subordinate proportion 

 of segerine-augite. Again, the chemical differences between the 

 garnet-pyroxene-malignite and the nepheline-pyroxene-malignite 

 are not of a radical kind, yet one rock- — that containing the smaller 

 proportion of soda — is rich in nepheline, while the other has none. 

 The rock containing the larger proportion of lime contains neither 

 garnet nor plagioclase, while that with the less lime has considerable 

 plagioclase and abundant garnet. 



As regards structural variations, the most interesting point is 

 that connected with the relative order of crystallization of the 

 orthoclase in different types of the rock. In the nepheline-bearing 

 rock it was clearly the last to crystallize, and forms a mesostasis 

 in which other constituents are imbedded poikilitically. In the 

 garnet-bearing rock quite the reverse is the case, since the bulk 

 of the orthoclase is in the form of the huge porphyritic crystals 

 imbedded in a paste of the other minerals. If we suppose that 



