Yanadiferous Minerals in Western Colorado. 141 



The results, however, show a great lack of agreement and 

 wide variation. It is plain that no probable formula can be 

 calculated for the yellow body. The variations are of such a 

 nature as to indicate in the plainest manner that it is a mixture 

 of several substances. 



Such a detailed discussion as the foregoing would hardly 

 have been justified in view of the negative conclusions arrived 

 at, but for the fact that Messrs. Friedel and Cumenge in their 

 paper announced a simple formula for the body examined by 

 them and gave it the specific name carnotite. Their published 

 analyses are as given below, from which they have excluded 

 considerable sand and traces of barium, aluminum, lead, copper, 

 and radio-active bodies as present in excessively small quanti- 

 ties. They make no mention of calcium, and admit that their 

 values for water are open to doubt. The formula deduced by 

 them is 2iJ 9 8 ,* Y 2 6 , K 2 0, 3H 2 0. 



Analyses of Carnotite by Friedel and Cumenge. 

 Found. 



u 2 o 9 *---- 



... 64-70 



62-46 



~" 



Calculated. 

 63'54 



v,o. 



... 20-31 



19-95 





20-12 



K 2 



... 10-97 



11-09 





10-37 



H 2 





5-29 



•481 



5-95 



Fe.0,— - 



•96 



•65 







99-98 



It appears from these analyses that Messrs. F. and C. by 

 great good fortune obtained a variety of samples of the pure 

 potassium compound, free from calcium and without appre- 

 ciable admixture of barium. This is very remarkable in view 

 of the fact that all the ores from different localities examined 

 by me show large admixture of calcium or barium salts or both, 

 even that which is certified to have come from the same lot as 

 that from which their material was taken. The French authors 

 give a brief outline of their methods of analysis. That one 

 which afforded them the best results would involve the weigh- 

 ing of any calcium present as sulphate along with the potas- 

 sium, on the assumption that the presence of that element had 

 been overlooked. It is much to be desired that a re-analysis of 

 their material should be made, if there is any of it still avail- 

 'able, in order to clear up the doubt connected with the first 

 analysis. 



In the light of the evidence herein set forth, the existence 

 of a distinct mineral species having the composition claimed 

 for carnotite can by no means be considered as established. 



*01d notation equivalent to the modern U0 3 . 



