Buddington — Natural and Synthetic Melilites. 51 



40 2CaO.Mg0.2Si0 2 — 60 [(90 3CaO.Al 2 3 .3Si0 2 ) (10 3Na 2 O.Al 2 3 .3Si0 2 ) ] 



Phases 



Homogeneous fibrous aggregate. 



Essentially homogeneous; trace of intersti- 

 tial second crystal phase in some grains. 

 Much air; fibrous aggregate. 



no = 1.630 ne— 1.628 



More distinct trace of interstitial higher bire- 

 fringent material. Clear of air. 



Two crystal phases; approximately half and 

 half. 



Glass plus trace crystals. 



All glass. 



Temperature 

 1075° 

 1100° 



Time 

 40 hrs, 

 2 hrs, 



1130° 



3 hrs. 



1210° 



16 hrs. 



1328° 

 1331° 



1/3 hr. 



1/3 hr. 



Temperature Time 

 980° 16 hrs 



20 2CaO.Mg0.2Si0 2 — 80 [(90 3CaO.Al 2 3 .3Si0 2 ) (10 3Na 2 O.Al 2 3 .3Si0 2 ) ] 



Phases 

 Fibrous and bladed aggregate. Homogeneous. 

 7ico = 1.632 n € — 1.622. 



Essentially homogeneous; trace of dissociation 



in some aggregates. 

 Trace of interstitial second crystal phase. 

 Glass plus trace crystals. 

 All glass. 



1100< 



1 hr. 



1130° 3 hrs. 

 1320° 1/3 hr. 

 1325° 1/3 hr. 



10 2CaO.MgO.2SiO, 



nperature 



Time 



1000° 



16 hrs. 



1125° 



40 hrs. 



1150° 



1 hr. 



90[(90 3CaO.Al 2 3 .3Si0 2 ) (10 3Na 2 O.Al 2 3 .3Si0 2 ) ] 



Phases 



Homogeneous, fibrous, and bladed aggregate. 



nia = 1.633 ne = 1.619 



Practically all homogeneous; trace of dissocia- 

 tion in some grains. 



Trace of dissociation and interstitial second 

 crystal phase. 



[ (90 3CaO.Al 2 3 .3Si0 2 ) (10 3Na 2 O.Al 2 3 .3Si0 2 ) ] 



Temperature Time 

 700° 144 hrs. 



980° 16 hrs. 



1000 c 



16 hrs. 



1100° 



2 hrs. 



1125° 



1 hr. 



1140° 

 1165° 



2 hrs. 

 168 hrs, 



Phases 



Still all glass. No trace of crystallization. 



Very fine grained fibrous aggregate. Trace of 

 wollastonite fibers believed to be due to im- 

 purity of melt or to exceptionally strong crys- 

 tallizing power of wollastonite. Otherwise 

 homogeneous. 



Very well crystallized material. Eibbed and 

 bladed aggregates and coarse laths. Trace of 

 feather-like crystals, probably wollastonite. 



n<a— 1.631 ne = 1.615 



Trace of dissociation in some grains, mostly 

 homogeneous fine-grained fibrous aggregate. 



Very fine grained fibrous granular aggregate 

 with interstitial strong birefringent material 

 forming second crystal phase. 



Trace of dissociation very distinct. 



Coarse blades and laths, with interstitial disso- 

 ciated material and a trace of glass. 

 raw = 1.640 ne = 1.616 



