166 JST. L. Bowen — Crystallization of Haplobasaltic, 



points representing the composition of liquids which can exist 

 in equilibrium with plagioclase crystals, and the other all 

 points indicating the composition of liquids which can exist in 

 equilibrium with diopside. There should, presumably, be but 

 a single boundary curve separating these fields and indicating 

 the composition of all liquids which can exist in equilibrium 

 with both plagioclase and diopside. This is the condition 

 actually found and shown in fig. 4. Thus the field AED 



Fig. 4. 



ANORTHITE 



contains all points representing the composition of all liquids 

 which can exist in equilibrium with (are saturated with) diop- 

 side and DECB is the corresponding field for plagioclase. 



By means of isotherms we may indicate also the temperatures 

 at which various liquids become just saturated with either solid 

 phase (temperatures of beginning of crystallization), and this 

 has been done in fig. 5. The quenching results on which the 

 location of the isotherms and boundary curve rests are given in 

 Table III. 



Figure 5 may be regarded as a contoured map of a solid 

 model showing fusion surfaces which represent the tempera- 

 ture of saturation (beginning of crystallization) for the various 

 compositions, temperature being plotted vertically and compo- 

 sition horizontally on triangular coordinates. A vertical sec- 

 tion of such a model along the direction of the boundary curve 

 is shown in fig. 6. 



