Foote and Bradley — Chemical Composition of Analcite. 433 



Art. XXXYI. — On Solid Solution in Minerals. II — The 

 Chemical Composition of Analcite / by H. W. Foote and 

 W. M. Bradley. 



The mineral analcite is the most important normal meta- 

 silicate among the zeolites and occurring, as it does, in excel- 

 lent crystals, its chemical composition has been the subject of 

 repeated investigations. The formula which has been derived 

 from the analyses, and which is commonly accepted, is !Na 2 Al 2 

 (Si0 3 ) 4 .2H 2 0. A consideration of the ratios derived from 

 many analyses will show, however, that this formula is not in 

 good agreement with the facts. This is well illustrated in 

 Table I, in which the ratios of all the analcite analyses given 

 in Dana's Mineralogy have been calculated. 



Table I. 

 Eatios obtained from Analyses of Analcite given in Dana's Mineralogy. 



No. 



1. 



2. 



3. 



4. 



5 



G. 



7 



8 



9 

 10. 

 11 

 12. 

 13 

 14. 

 15 

 16. 

 17 

 18 

 19 

 20 

 21 

 22 

 23 



Si0 3 

 4*70 

 4-30 

 5'35 

 4-39 

 4*39 

 4-17 

 4-25 

 4-26 

 3-89 

 3-77 

 3-67 

 3-57 

 3-74 

 4*05 

 4-49 

 4-00 

 4*15 

 4-27 

 3-76 

 4'48 

 4-02 

 4-03 

 4-11 



A1 2 

 1 

 1 

 1 



1 

 1 

 1 



etc. 

 •16 

 •07 

 •23 

 •LI 

 •01 

 •06 

 •94 

 •14 

 •99 

 •97 

 •97 

 •93 

 •02 

 •07 

 •09 

 •00 

 •98 

 •01 

 •97 

 •14 

 •01 

 •00 

 •07 



Na 2 

 1 



O, etc. 

 •00 



H 2 



2-37 



2-15 



1-62 



2-22 



2-30 



2-17 



2-08 



2-25 



1-96 



2-14 



1-91 



1-81 



1-94 



2-10 



2-49 



2-04 



2-14 



15 



•00 



•36 



•03 



•00 



14 



It is impossible to judge of the value of many of the analyses 

 whose ratios have just been given, for in the original descrip- 

 tions there is usually either no statement made regarding the 

 quality of the material analyzed or the analysis was primarily 

 undertaken to show that analcite was a constituent of certain 



