4:12 Andersen — System Anorthite-J^orsterite-Silica. 



Table 2. 

 The System Anorthite-Silica.* 



Composition 

 in weight per cent. 



Compounds 



An 



80-00 



70-00 



51-00 



SiO, 



20-00 



30-00 



49-00 



Oxides 



Si0 2 



54-60 



60-27 



71-06 



Al 2 Oa 



29-32 



25-66 



18-69 



CaO 



16-08 



14-07 



10-25 



Tem- 



Time 



pera- 

 ture 



heated 

 in 



in 



degrees 



hours 



1486 



* 



1490 



i 



1440 



i 



1445 



i 



1351 



2 



1355 



2 



1361 



2 



1368 



2 



Results 



G1& An 

 Gl only 



Gl & An 

 Gl only 



TF&~An 



Gl & Tr 

 Gl & Tr 

 Gl only 



* This system has been described by G. A. Rankin and F. E. Wright in 

 their work on the CaO-Al 2 03-Si0 2 system. (This Journal (4), xxxix, 1, 

 1915.) 



The results, stated in this table, agree very closely with those of Rankin 

 and Wright, who find the eutectic An : Tr at 1359° of composition An 52*5 

 Si0 2 47-5. 



Table 3. 

 The System Anorthite-Forsterite. 



Composition. 

 in weight per cent. 



Com- 

 pounds 



An Fo 



90 



86 



80 



70 



60 



54 



50 



40 



10 



14 



20 



30 



40 



46 



50 



60 



Oxides 



Si0 2 A1 2 3 CaO MgO 



43-20 



43-1 



43-16 



43-11 



43-06 



43-03 



43-02 



42-97 



32-99 



31-52 



29-32 



25-65 



21-99 

 19-79 



18-32 



14-66 



18-09 

 17-29 



16-08 



14-07 



12-06 



10-85 



10-05 



8-04 



5-72 



8-01 



11-44 



17-17 



22-89 



26-33 



28-61 



34-33 



Tempera- 

 ture in 

 degrees 



1463 



1468 



1442 

 1446 



1457 

 1463 



1478 



1475 

 1481 



1462 

 1470 



1513 

 1519 



1618 

 1622 



Time 

 heated 

 in hours 



Results 



* 



i 



G1& An 

 Gl only 



1 



"2 



i 



Gl,An&Sp 

 Gl only 



1 

 2 

 1 



Gl&Sp 

 Gl only 



i 



Gl & traces 

 of Sp 



i 

 i 



G1& Sp 

 Gl only 



i 

 i 



Gl, Sp & Fo 

 Gl only 



1 

 "2 

 1 

 2 . 



Gl & Fo 

 Gl only 



i" 



i 



Gl&Fo 

 Gl only 



