22 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 



exact as are warranted by the errors due to the uncertainty of the 



constituent minerals of the analyzed material and to the faults of 



analysis. 



As an example of the process of calculation, analysis 37 may be 



taken : 



Analysis of wolframite from Hill City, S. Dak. 



Tungsten trioxide (WO 3 ) 71. 



Ferrous oxide (FeO) 14. 3 



Manganous oxide (MnO) 10. 2 



Lime (CaO) 0. 7 



Silica (SiO 2 ) 2. 9 



Magnesia (MgO) None. 



Water (H 2 O) 0. 3 



99.4 

 W0 3 

 CaO CaO WO, 



0.7 X 4.14 = 2.9 



CaO WOs CaW0 4 



0.7+2.9 =3.6 



WO 3 

 MnO MnO WO, 



10.2 X 3.27 = 33.4 



MnO W0 3 MnWO* 



10.2 + 33.4 = 43.6 

 WO 3 required to satisfy the CaO and MnO 36.3 



WO 3 in analysis 71.0 



Less quantity for CaO and MnO 36. 3 



WO 3 to be satisfied by FeO 34. 7 



FeO in analysis 14, 3 



FeO required 10. 8 



Excess of FeO 3.5 



Adding the MnWO 4 and FeWO 4 , 



Hiibnerite (MnW0 4 ) 43. 6 



Ferberite (FeWO 4 ) 45. 5 



Theoretical wolframite in the material analyzed 89. 1 



