E. T. Wherry — New Occurrence of Carnotite. 579 



to 0'21 per cent V 2 3 . These specimens were free from any 

 visible admixture of carnotite, and that no microscopic inclu- 

 sions of such a mineral were present was proved by the insolu- 

 bility of the vanadium in nitric acid, as well as the absence of 

 proportionate amounts of uranium, noted in the succeeding 

 paragraph. This vanadium probably replaces other sesquiox- 

 ides in the silicates ;* and as the fine state of division of the 

 latter renders them easily attacked by surface waters, oxidation 

 of the vanadous compound and development of some second- 

 ary vanadate is the natural thing to expect. 



Uranium is also present in the metamorphic rocks of the 

 New York-Pennsylvania Highlands, as shown by the radio- 

 activity! of several widespread minerals, such as allanite and 

 zircon, as well as the occasional appearance of columbite, 

 uraninite, etc. Because of analytical difficulties no attempts 

 have been made to determine its proportion in these rocks as a 

 whole, but it may perhaps mount into the hundredths per cent. 

 On the disintegration of the rocks, as described above, the 

 uranium-bearing minerals wonld, of course, be expected to 

 accumulate in the black sand lenses, along with those carrying 

 the vanadium. Chemical examination showed, however, only 

 about 0*002 per cent of U0 3 to be present, an amount whose 

 concentration by circulating waters seems rather unlikely. It 

 is not impossible that some of the pebbles of the conglomerate 

 may contain uranium minerals, but no definite evidence of 

 this has been, or, in the nature of the case, is likely to be, 

 obtained, so that the immediate source of the uranium enter- 

 ing into the carnotite remains obscure, although in the total 

 absence of deep-seated vein phenomena there can be little 

 question as to its ultimate derivation in some manner from the 

 sediments. 



The conclusion to be drawn from these studies is, then, that 

 the development of the carnotite at this locality has been made 

 possible by mechanical concentration of uranium and vanadium 

 minerals originally distributed through large bodies of crys- 

 talline rocks, brought about by a sudden change from a dry to 

 a moist climate. To claim an identical origin for the deposits 

 in Colorado and Utah would be hazardous, yet the published 

 descriptions show that they also occur in arenaceous forma- 

 tions overlying u Red Beds," and if similar climatic changes 

 were responsible for the change in character of the sedimenta- 

 tion there, it is quite possible that the concentration of the 

 constituents of the mineral has been brought about in the same 

 manner. 



Indeed, it may be permissible to suggest that the frequent 



* Cf. Hillebrand, loc. cit. 



f Wherry, Jour. Frank. Inst., vol. clxv, pp. 59-78, 1908. 



