Diopside — Forsterite — Silica, 



217 



Fig. 6. 



CaMgSi 2 6 



PRIMARY PHASE 

 DETERMINED POINTS* BSSwKP 



• SILIC* 



SO 



General Character of the Fusion Surfaces. 



In fig. 5 the boundary curves are drawn in accordance with 

 the results stated in Table III. In fig. 6 the determined 

 points are indicated and the isostherms drawn as far as they 

 are fixed by these points. All points on the pyroxene surface 

 are determinable by the quenching method. In the forsterite 

 field and in the silica field only points below 1625° (usually 

 below 1580°) were determined. The pyroxene surface is one 

 of relatively gentle gradient, falling from the more magnesian 

 mixtures towards the more calcic. The forsterite surface mounts 

 steeply towards forsterite (melting-point 1890°). The silica 

 surface mounts still more steeply, in its determinable part, 

 towards silica. 



