68 Buddington — Natural and Synthetic Melilites. 







Table XVIII. 









ATcermanite from Vesuvius, 







Calculation from Zambonini's analysis. 





• 



Original 

 analysis 



Analysis 

 reduced 



2CaO.Mg0.2Si0 2 



and 

 Mol. 3CaO.Al 2 3 .3Si0 2 

 molecules 



Difference 



SiO, . 

 A1 2 3 . 

 CaO .. 

 MgO . 

 FeO . 



. . . 46.55 

 .. . .96 

 ... 39.30 

 . . . 13.30 

 .12 



46.33 



1.08 



39.31 



13.28 



7683 6908 



106 106 



7020 6908 



3295 3295 



—775 

 —112 





100.23 



100.00 





Gehlenite. 



Gehlenite of Velardena.- — The gehlenite described by 

 Wright 14 from Velardena, Mexico, approximates more 

 closely in composition the compound 2CaO.Al 2 3 .Si0 2 

 than any of the other gehlenites described. According 

 to Wright it is associated with colorless pyroxene, yellow 

 garnet, magnetite, rutile, and spurrite, and is formed at 

 the contact of a basic intrusive diorite and limestone. 



Table XIX. 



Gehlenite from Velardena, Mexico. 





Original 



Analysis 





Calculated 







analysis 



reduced 



Mol. 



molecules 



Difference 



SiO, ... 



... 26.33 



26.76 



4438 



4438 





A1 2 3 . . 



. . . 27.82 



28.27 



2771 



2779 



+ § 



CaO ... 



. . . 39.55 



40.19 



7177 



7158 



—19 



MgO . . 



. . . 2.44 



2.48 



615 



623 



+ 8 



TiO, . . . 



.03 



,03 



4 





— 4 



Fe 2 3 .. 



. . . 1.43 



1.45 



81 



80 



— 1 



FeO ... 



.50 



.50 



70^ 



72 



— 1 



MnO .. 



.01 



.01 



1! 



Na,0 . . 

 K,6 ... 



.21 



.10 



.21 



.10 



34 j 



10 j 



44 





HoO .. 



. . . . 1.85 













100.27 



100.00 





In Table XIX is given the analysis by Allen of this 

 gehlenite from Velardena, Mexico, reduced, with elimina- 



14 F. E. Wright, this Journal, 26, 545-7, 1908. 



