Buddington — Natural and Synthetic Melilites. 61 



Table XI. 



Optical and thermal data for mixtures of 10 percent 3Na 2 O.Al 2 3 .3Si0 2 with 



varying percentages of 3CaO.Al 2 3 .3Si0 2 and 3CaO.Fe 2 3 .3Si0 2 . 



Compositions in weight percent. 



3Na,,0. 



3CaO. 



3CaO. 





Glass -|- 







Al 2 6s. 



A1 2 3 . 



FeA. 





trace of 



All 





3Si0 2 



3Si0 2 



3Si0 2 n w 



ne 



crystals 



glass 





10 



90 



00 1.631 



1.615 



1327° 



1334° 



Inhomogeneous 



10 



81 



9 *1.642 



*1.632 







(40hrs.atl000°) 



10 



67.5 



22.5 *1.655 



*1.637 



1270° 



1275° 



Inhomogeneous 



(16hrs.atll25°) 



Inhomogeneous 



10 



54 



36 









(16hrs.atll60°) 



* Determined on dominant crystal phase. 



Table XII. 



Optical and thermal data for mixtures of 10 percent 3Na 2 O.Al 2 3 .3Si0 2 with 



varying percentages of 2CaO.Mg0.2Si0 2 ;3CaO.Al 2 3 .3Si0 2 ; and 



3CaO.Fe 2 3 .3Si0 2 . Compositions expressed 



in weight percent. 



*Essential- 



ly one Trace of Glass -f- 

 crystal disso- Trace of All 

 phase, ciation. crystals. 

 1140° 1170° 



(20 hrs.) 

 1160° 1170° 

 (1 hr.) (16 hrs.) 

 1150° 1170° 

 (lhr.)(16hrs.) 

 1150° 1170° 

 (16 hrs.) (1 hr.) 

 1140° 1170° 



(20 hrs.) (16 hrs.) 



1140° 1165° 



(16 hrs.) (1 hr.) 



1140° 1160° 



(lhr.)(lhr.) 



+1000° 1125° 



(40 hrs.) (16 hrs.) 

 Inhomogeneous 1316° 1320° 



(16 hrs. at 1110°) 

 Inhomogeneous 



(16 hrs. at 1000°) 

 Inhomogeneous 



(16 hrs. at 1170°) 



Inhomogeneous 1285° 1291° 



(16 hrs. at 1150°) 

 Inhomogeneous 

 (4 hrs. at 1040°) 



* These preparations are not completely homogeneous as they contain a 

 trace of minute grains of much higher indices of refraction. It is believed, 

 however, that the inhomogeneity is so slight that the crystals are of essen- 

 tially the same composition as the melt, except in the case of those mixtures 

 marked inhomogeneous. 



t Completely homogeneous. a Determined on dominant crystal phase. 



3Na2O.2CaO.3CaO 3CaO. 

 A1 2 3 . MgO. FeA AL0 3 . 

 3Si0 2 2Si0 2 3Si0 2 3Si0 2 no, 



n e 



10 



54 



27 



9 



1.663 



1.648 



10 



45 



27 



18 



1.663 



1.648 



10 



54 



18 



18 



1.651 



1.641 



10 



40 



18 



' 32 



1.650 



1.640 



10 



38 



14 



38 



1.645 



1.638 



10 



40 



10 



40 



1.639 



1.635 



10 



27 



9 



54 



1.640 



1.632 



10 



18 



9 



63 



1.642 



1.633 



10 



47 



33 



10 



*1.671 



al.653 



10 



63 



13.5 



13.5 



al.643 



al.640 



10 



36 



36 



18 







10 



30 



30 



30 







10 



34 



22 



34 



al.655 



al.645 



1329° 1335 c 



1311° 1316° 

 1308° 1315° 



