Haplodioritic and Related Magmas. 185 



Summary. 



Mixtures of diopside with various members of the plagio- 

 clase series, referred to as haplobasaltic,* haplodioritic and so 

 forth, according to the nature of the plagioclase, are studied by 

 the quenching method of thermal analysis. Equilibrium, 

 determined in this manner, is represented graphically in several 

 diagrams. All the determinations which are necessary for the 

 complete description of the crystallization of any mixture have 

 been made and are presented. 



The facts determined for haplodiorite and so forth are 

 applied to their natural analogues and it is shown that there 

 can be little reason to doubt that crystallization controls the 

 differentiation of the subalkaline series of igneous rocks. 



Geophysical Laboratory of the Carnegie Institution of Washington. 



* From the Greek anlooc; = simple. 



