.",(14 



Rankin (ind Merwin — 



MgO-Si02« 



Fig. 1. 

 S1O2 



'„t2 MgO-2Ai203-5S.02 



2MgOSi0 2 / 



/ 



,Al 2 03-SO2 



6\* 



,---\ -'- 



MgO 



MgO-Al 2 03 



A12O3 



Table 1. 



Quenehings which determine the limits of the field of spinel (MgO.ALO-) ' ; 



see also Table 8. 

 Pliases present, glass -\- spinel. 



( Composition 



Weight Per cent 



Temp. 



Time 



MgO 



ALO, SiO, 





in hours 



220 



730 5-0 



1900 2 





150 



80-0 50 



1900 2 





150 



600 250 



1750 2 





550 



180 270 



1750 2 





490 



210 300 



1700 2 





370 



230 400 



1600 



•25 



390 



210 400 



1600 



•25 



170 



380 450 



1475 



•5 



300 



250 450 



1450 



•5 



250 



240 510 



1375 



•5 



1 Formulas written thus are ideal. The 



actual crystals 



formed in parts 



of the field may ha 



ve quite a different composition. In the case of spinel 



solid solution is extensive. 







2 Iridium furnace 



melt. 







