76 Eanhin and Wright — Ternary System CaO-Al 2 0-Si0 2 . 



A. Compounds — Transformation Points. 





Weight percentage 







Formula 



CaO 



A1 2 2 



Si0 2 



Transformation 



Temp. 



CaO 



loo- 







Melting 



2570°* 



A1 2 3 





100- 





u 



2050° * 



Si0 2 







100- 



a 



1625° f 



Si0 2 







100- 



Tridymite to 

 cristobalite 

 and reverse 



1470° f 



aCaO.Si0 2 



48-2 





51-8 



Melting 



1540°±2° 



CaO.Si0 2 



48-2 





51-8 



a to ft and reverse 



1200°±2° 



o2CaO.SiO Q 



65' 





35* 



Melting 



2130° ±20° 



2CaO.Si0 2 



65' 





35- 



y to (3 and reverse 



675°±5° 



2CaO.Si0 2 



65' 





35- 



ft to a and reverse 



1420°±2° 



3Ca0.2Si0 2 



58-2 





41-8 



Dissociation into 



a2CaO.Si0 2 



and liquid 



1475°±5° 



3CaO.Si0 2 



73-59 





26*41 



Dissociation into 



a2CaO.Si0 2 



and CaO 



1900° ±20° 



3CaO.Al 2 3 



62-22 



37-78 





Dissociation into 

 CaO and liquid 



1535°±2° 



5Ca0.3Al 2 3 



47-78 



52-22 





Melting 



1455°±5° 



CaO.Al 2 3 



35-44 



64-56 





a 



1600° ±5° 



3Ca0.5Al 2 3 



24-78 



75-22 





a 



1720° ±10° 



Al 2 3 .Si0 2 





62-85 



37-15 



a 



1816°±10° 



CaO.Al 2 3 .2Si0 2 



20-09 



36-63 



43-28 



a 



1550°±2° 



2CaO.Al 2 3 .Si0 2 



40*83 



37-19 



21-98 



a 



1590°±2° 



3CaO.Al 2 3 .Si0 2 



50*9 



30-9 



18-2 



Dissociation into 

 £CaO.Si0 2 

 andCaO.Al 2 3 



1335°±5° 



*Kanolt, J. Wash. Acad. Sci., iii, 315, 1913. 

 f Fenner, this Jour. (4), xxxvii, 331-384, 1913. 



