Buddington — Natural and Synthetic Melilites. 



63 



Table XV. 



Optical characters and thermal data of mixtures containing 10 percent 



3Na-O.Alo0 3 .3SiO, and 20 percent 2CaO.AL0 3 .Si0 2 with varying 



percentages of 3CaO.AL0 3 .3Si0 2 and 3CaO.Fe 2 3 3Si0 2 . 



Compositions expressed in weight percent. 



3NaA 2CaO. 3Ca0..3CaO. 

 AL0 3 . AL0 3 . A1 2 3 . Fe 2 3 . 



3SiO, 



10 



10 

 10 

 10 



SiO, 



20 



20 

 20 

 20 



3 SiO. 3 SiO., nco 

 70 00 1.638 



1.653 

 1.657 



56 

 49 

 42 



14 

 21 



28 



lie 

 1.624 



1.640 

 1.645 



Inhomogeneous 

 (16hrs.atll25°) 



One Trace of 



Glass -f- 





crystal disso- 



Trace 



All 



phase. ciation. 



crystals 



glass. 



1140° 1160° 



1412° 



1417° 



(2hrs.)(16hrs.) 







1142° 1160° 



1380° 



1386° 



(20 hrs.) (40 hrs.) 







1145° 1160° 



1360° 



1366° 



(2 hrs.) (1 hr.) 









1344° 



1350° 



Table XVI. 



Dptieal characters and thermal data of mixtures containing 10 percent 3Na20.Al 2 3 .3Si0 2 



and 20 percent 2CaO.Al 2 3 .Si0 2 with varying percentages of 2CaO.Mg0.2Si0 2 ; 



3CaO.Al 2 3 .3Si0 2 ; and 3CaO.Fe 2 3 .3Si0 2 Compositions in 



weight percent. 



JNa,0. 2CaO. 2CaO. 3CaO. 3CaO. 



Mo6 z . A1,0 3 - MgO. Fe,0 3 . Al,O s . 



SSi0 2 Si0 2 2Si0 2 3Si0 2 3Si0 2 n<a 

 10 20 10 10 50 1.648 



10 20 30 10 



10 20 21 21 



10 20 28 2S 



10 20 7 28 



10 20 21 35 



10 20 35 21 



1.648 

 1.660 

 1.671 

 1.671 

 14 *1.680 

 14 *1.661 



Crystals Glass 

 One Trace plus plus 



crystal disso- trace trace 



ne phase, ciation. glass. crystals. 



1.638 1155° 1175° 1376° 



(lhr.)(lhr.) 

 1.642 1225° 

 (lhr.) 

 1.649 1200° 1220 

 (lhr.)(i/ 2 hr.) 



1.657 1220° 



(lhr.) 

 *1.656 Bare trace inhomog. 



(lhr. at 1147°) 

 *1.663 Bare trace inhomogeneity 



(16 hrs. at 1150°) 

 *1.653 Trace of inhomogeneity 



1240° 

 (lhr.) 



1235° 

 (lhr.) 



1358° 

 1328< 

 1310 c 

 1334° 



All 



glass. 

 1382° 



1364° 



1335° 



1316° 



1342° 



'Determined on major crystal phase, which lacks but little of complete homogeneity. 



plotted. Fig. 10 similarly shows the indices of refraction 

 plotted against composition in weight percent for the 

 solid solutions consisting of 10 percent 3Na 2 O.Al 2 3 . 

 3Si0 2 and variable amounts of 2CaO.Mg0.2Si0 2 and 

 3CaO.Alo0 3 .3SiOo, within a temperature range above 

 1000 : . Mixtures" of 3CaO.Al 2 3 .3Si0 2 and 3CaO.Fe 2 3 . 

 3Si0 2 with as little as 10 percent of the latter constituent, 

 showed some inhomogeneity, as they did also at all higher 

 percentages investigated. 



