COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 23 



Recalculating to percentages of the theoretical wolframite and then 

 breaking up into oxides, 



Hiibnerite (Mn\V0 4 ) ...................... 48. 9=11. 5 MnO+37. 4 WO, 



Ferberite (FeWO 4 ) ........................ 51. 1=12. 1 FeO +39. WO, 



Total WO 8 in theoretical wolframite ................... 76. 4 



The presence of water (0.3) in the analysis probably indicates that 

 a part of the apparent excess of FeO (3.5) is limonite. The 0.3 per 

 cent of water will combine with 1.6 per cent of FeO to form 2.1 per 

 cent of limonite, considered as 2Fe 2 O 3 .3H a O. This still leaves an 

 excess of 1.9 per cent FeO. 



Summarizing, the calculation shows the wolframite to have a com- 

 position of 



51.1 



48 - 9 



With which is associated in the mass scheelite, CaWO 4 , 3.6; excess 

 FeO, 1.9; limonite, 2.1. 



