Yanadiferous Minerals in Western Colorado. 133 



Considering that the mineral is probably not perfectly pure 

 and the uncertainties affecting the amount of water to be con- 

 sidered, etc., the above affords a close approach to the typical 

 phengitic muscovite formula H^KR/", X 3 in which X comprises 

 the groups Si0 4 and Si 3 8 . 



Analysis of the vanadiferous sandstone. 



Soluble 



in 



Nitric acid. 



Sandstone. 

 Per cent. 



SiO„ 12-56 



Ti0 2 '02 



V 2 3 3-50* 



Al s O, 6-15 



Fe 2 3 .. -20 



CaO.__ -12 



BaO -37 



MgO -25 



K Q 2-41 



Na 2 -06 



H o at 105° .. -54 



H 2 105°-300° -14 



H 2 above 300° -97 



UO s -05 



PbO -06 



^V 2 5 -05 



Insoluble f Quartz, etc. .. 72*24f 



in ^ H o at 105° __ -04 



Nitric acid. ( H 2 above 105° -20 



Ratios. 

 •763 



•0846 

 •2206 

 •0046 

 •0078 

 •0088 

 •0228 

 •0938 

 •0035 

 •1100 

 •0283 

 •1978 



Silicate. 

 Per cent. 



46-06 



•305 



12 



22 



•039 1 



•097 8 



•198 3 



84 

 55 



73 FeO 



44 



35 



92 

 84 

 22 

 98 

 51 

 56 



Roscoelite. 



45-17 



•78 



24-01 



11-54 



1-60 



1-64 



10-37 



•06 



•40 



•17 



4-12 



100-00 



99-86 



99-93 



Traces of Li, Cu, Mo, Bi. No CI, S0 3 , or P 2 5 . 



An attempt to satisfactorily distribute the constituents 

 among different chemical molecules would be futile, since, for 

 instance, we do not know whether to ascribe the barium to a 

 biotite or muscovite molecule, but the close approach to the 

 muscovite ratio leaves little room to doubt the character of the 

 body. Notwithstanding the chloritic aspect of the mineral 

 under the microscope, the analysis shows that it cannot be a 

 chlorite, and we have undoubtedly to do with a body closely 

 related to the mica roscoelite, wherein, however, the percentage 

 proportions of A1 2 3 and V 2 3 are reversed, thus affording a 

 further striking example of the mutual replaceability of these 

 two oxides. 



* Oxidation by permanganate of the HP1 and H 2 S0 4 solution of the sandstone 

 indicated 3-43 per cent V 2 3 (mean of 3-50, 3-32, 3-48, 3-43). 



\ Containing about 65 per cont Si0 2 , 7 per cent A1 2 3 (Fe 2 3 , Ti0 2 ) and about 

 0-3 per cent of zircon and other minerals not decomposed by repeated evapora- 

 tions with HF1 and H 2 S0 4 . ': 



