Andersen — System Anortli ite-Forsterite-Silica. 435 



out. For some melts it may happen (as is shown above) that 

 the crystallization curve breaks away from the alteration curve 

 before the quintuple point o is reached. In the diagrams 

 alteration curves are indicated by double arrows,* whereas 

 single arrows indicate ordinary boundary curves, melting 

 curves. 



Fig. 8. 



m 



-> 



<■ 



if 



<r 



B 



i D 



Apart from what is mentioned concerning the boundary 

 curve y o the relations of the present type of ternary systems 

 are not different from those of Type 3. The course of crystal- 

 lization in different sections of the system is easily inferred 

 from the diagram by means of the rules now repeatedly 

 applied. 



Type 5. 



The present type is a modification of Type 4. The only 

 essential difference between the two types lies in the shape of 

 *H. E. Boeke, Centralbl. Min., 1912, 275. 



