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JOURNAL OF GEOLOGY—SUPPLEMENT 



by a point on the line AP) become completely crystalline at the 

 temperature of the point N, the last minute quantity of liquid 

 having the composition iV^. A mixture of pyroxene L with forster- 

 ite (i.e., any composition lying on the join AL) would, however, 

 become completely crystalHne at the higher temperature K, and the 

 last minute quantity of liquid would have the composition K. A 

 mixture of pyroxene T with forsterite (i.e., any composition lying 



Fig. 3. — Crystallization curves for the system: diopside, forsterite, silica 



on the join A T) would become completely crystalline at a tempera- 

 ture lower than N, and the last of the hquid would be more calcic 

 than N. 



Thus any mixture represented by a point on any line passing 

 through A has a temperature of final crystallization different from 

 that of a mixture lying on any other line through A , and the compo- 

 sition of the final liquid is different in each case. There is, more- 

 over, in each case a continual change in the composition of the 



