456 F. N. Guild — Composition of Molybdite from Arizona. 



Deducting- the insoluble residue and recalculating the anal- 

 yses, we have 



No. 1 No. 2 Average Ratio 



H 3 17'69 17-02 17-355 7-06 



Fe„0 3 21-97 21-70 21-835 1- 



MoO s 60-34 61-27 60-805 3"09 



The empirical formula calculated from the above figures 

 is Fe 9 O y 3Mo 3 .7M, O, or, Fe/Mo OJJK O. With the excep- 

 tion of the water of crystallization, these results are identical 

 with those obtained by Mr. Schaller on samples from New 

 Hampshire, Ontario, Colorado and California. 



