116 



10000 



The FeO and MgO are probably present as isomorphous 

 tungstates, and the mineral composition is then as follows : — 



Per Cent. 

 CaWO. .. .. .. .. 97-63 



101 



FeW0 4 

 MgW0 4 



1-36 



10000 

 The commercial scheelite of Otago is thus not the pure calcium 

 compound. The absence of manganese indicates that there is 

 no admixture of wolfram. 



The mineral carries distinct traces of molybdenum in varying 

 quantities up to 1 per cent. The methods used in estimating 

 this constituent were those of Rose,* of Ruegenberg and Smith, f 

 and of Ibbotson and Brearley.f A search was made for cerium 

 and the other rare earths, both chemically and spectroscopically, 

 but with negative results. 



Analyses by Traube§ of scheelite from various localities are 

 here inserted for reference and comparison, and the universal 

 association of molybdenum is of peculiar interest. In his figures 

 for New Zealand scheelite, it will be observed that he records no 

 iron and no magnesia, but the particular locality from which 

 his samples were collected is not recorded. 



Locality. 



Zinnwald 



» 



Altenberg 



G. 

 5-88 

 603 

 601 

 603 

 606 

 607 



wo, 

 71-08 

 75-29 

 76-78 

 77-84 

 78-04 

 77-54 



MoO : ,. 



8-23 



3-98 



3-69 



2-23 



1-92 



2 03 



CaO. 



20-33 



20-34 



19-86 



19-48 



19-57 



19-91 



* H. Rose, Handbuch (1<t Anal. Choline (Sechte Auflage, 1ST I). 

 358. 

 •f- Ruegenberg and Smith, Journal Amer. ('hem. Sue, vol. xxii. |>. 77-. 

 J II)l)otson anil Bicarlcy. Journal ('hem. Soc. 1000, Alistr. ii. ]>. 445. 

 § J. D. Dana, " System of Mineralogy," Gth ed. (1800), p. 087. 



