312 



Rankin and Merwin- 



Table 14 (continued). 



Quenchings which determine temperatures for points on the boundary curves. 



Comp. Weight Per 



. cent 



MgO Al 2 O a SiO, 



Temp. Time 

 in 

 hours 



Phases present 



Bound- 

 ary 



370 

 260 



18-0 



220 



320 



270 



260 



25-5 



260 



250 



230 



210 



120 

 150 



14-0 



230 

 230 



30-0 

 25-0 

 110 

 18-0 

 200 

 21.0 

 210 

 200 

 200 

 18-0 



460 



44-0 

 47-0 



400 

 510 



520 



530 



570 



550 



540 



53-5 



530 



550 



570 



610 



42-0 

 410 

 39-0 



15 So 



25 



1600 



25 



1550 



5 



1376 1 







1370 1 







1365 



5 



1390 



5 



1360 1 







1362 



5 



1359 1 







1465 



5 



1450 



5 



1390 



5 



1370 



5 



1377 



5 



1370 



5 



1361 



5 



1360 



5 



1365 



5 



1360 



5 



1355 



5 



1350 



5 



1352 1 







1350 



5 



1360 



5 



1350 



5 



1575 





1575 





1600 





Glass -\- tr. 2MgO.SiO, -f tr. spinel 



Glass -j- spinel 



Glass + spinel -f 2MgO.SiO, 



Glass -j- spinel 



Glass -j- spinel + 2MgO.SiO, 4 



[cordierite 

 Glass -4- 2MgO.SiO, -f cordierite 

 Glass -j- cordierite 

 Glass -j- cordierite -f 2MgO.SiO, 

 Glass -j- cordierite 

 Glass -j- cordierite -4-2MgO.SiO. 

 Glass + 2MgO.SiO, 

 Glass -j- 2MgO.SiO., -f MgO.SiO, 

 Glass + 2MgO.SiO, 

 Glass -4- MgO.SiO, 

 Glass + 2MgO.Si6, 

 Glass + 2MgO.Si0 2 + MgO.SiO, 



Glass + 2MgO.SiO, -f MgO.SiO, 



Glass + 2MgO.SiO, 



Glass + 2MgO.SiO, + MgO.SiO, 



Glass + MgO.SiO, 



Glass -j- MgO.Si0 2 -|- cordierite 



Glass -j- cordierite 



Glass -j- cordierite 4- MgO.SiO, 



Glass -j- MgO.SiO, 



Glass 4- MgO.SiO, 4- cordierite 



Glass 4- Al,0 3 .SiO, 4- a A1,0 3 (tr.) 



Glass 4- spinel (tr.) 4- a A1 2 3 



Glass 4- spinel (tr.) -j- a A1 2 3 



Table 14a. 



4-5 



F-5 



5-1- 



C-7 

 B-7 



Quenchings which indicate a maximum on the boundary curve between 

 sillimanite and the ternary compound (cordierite). 



Phases present 



Glass 4- a ternary compound 

 Glass -j- a ternary compound 4- spinel 

 Glass 4- Al,0 3 .SiO, 



Glass 4- AL0 3 .Si0 2 (not yet resorbed) 4- ter- 

 [nary compound 4- spinel 

 Glass 4- ternary compound 

 Glass (?) 4- ternary compound 4- 2MgO.-SiO, 



[+? 

 Glass 4-Al,0 3 .SiO, 

 Glass 4- Al,0 3 .SiO, (not yet resorbed) 4- spinel 



The Quintuple Points. 



Of the seven quintuple points in this system, one 

 (point 1, fig. 1) is a well-established eutectic; another 



Comp. 

 MgO 



Weight 

 ALA 



Per 

 cent 

 SiO, 



Temp 



160 

 150 



330 



34-0 



51-0 

 510 



1460 

 1400 

 1465 

 1460 



180 



30-0 



520 



1400 

 1360 



14-4 



35-6 



50-0 



1525 

 1400 



