Composition wt. % 



Temp. 



in 



CaO MgO 



Si0 2 



°C. 



min. 



36 12 



52 



1368 



25 







1363 



25 



38 11 



51 



1366 



25 



37 12 



51 



1366 



15 



38 12 



50 



1375 



27 



Ferguson and Merwin — The Ternary System. 101 



ite, 5Ca0.2Mg0.6Si0 2 , and 2CaO.Mg0.2Si0 2 . The com- 

 position is CaO 36-7, MgO 12-3, Si0 2 51, and the tempera- 

 ture 1365 ± 5°C. 



Table V. 



Quenches which indicate the temperature relations at point 13. 



Time 



Phases present 



Glass + a CaO.Si0 2 



Glass + a CaO.Si0 2 + 5Ca0.2Mg0.6Si0 2 



Glass -j- aCaO.SiOo _j_ 5Ca0.2Mg0.6Si0 2 



Glass -f aCaO.Si0 2 



Glass If a CaO.Si0 2 + 2CaO.Mg0.2Si0 2 



Point 3 is a entectic between a5Ca0.2Mg0.6Si0 2 solid 

 solution, diopside and 2CaO.Mg0.2Si0 2 . Its composi- 

 tion is CaO 36, MgO 12-6, Si0 2 514, and its temperature 

 1350 ± 5°C. 



Table VI. 

 Quenches which determine the temperature relations at point 3. 



Time 

 Composition wt. % Temp. in Phases present 



CaO MgO Si0 2 °C. min. 



36 13 51 1345 30 No glass 



1350 30 Glass +5Ca0.2Mg0.6SiO, + 



CaO.Mg0.2Si0 2 + 2CaO.Mg0.2Si0 2 

 1354 120 Glass -f crystals 

 1348 120 Crystals -f merest trace if any of glass 



37 12 51 1351 20 All crystals 



1353 30 Glass + crystals 



Point 4 is a eutectic between 2CaO.Mg0.2Si0 2 , forster- 

 ite and diopside. The composition is CaO 29-8, MgO 

 20-2, Si0 2 50, and the temperature 1357 ± 5°C. 



Table VII. 

 Quenches which determine the temperature relations at point 4. 



Time 

 Composition wt. % Temp. in Phases present 



CaO MgO Si0 2 . °C. min. 



29 21 50 1354 30 No glass 



1359 20 Glass -f crystals 



30 20 50 1354 15 No glass 



1359 20 All glass 



Point 6 is a eutectic between pseudowollastonite, 3CaO. 

 2Si0 2 and 2CaO.Mg0.2Si0 2 . Its composition is CaO 

 49-2, MgO 6-3, Si0 2 44-5, and its temperature 1377 ± 5°C. 



