466 ■ Watson— Occurrence of Uranophane in Georgia. 



IJ(U0 4 ) 2 61-28, corresponding to 60-14: per cent of U0 3 ; CaO 

 6-01. 



Accepting then the percentages of Si0 2 and H 2 in the first 

 analysis, and those of TT0 3 and CaO in the last, as representing 

 the composition of the mineral ; and disregarding the percent- 

 ages of Fe 2 3 , A1 2 3 , MgO and P 2 5 , and recalculating the four 

 essential oxides to a basis of 100, the ratios become : 



III. 



I. II. , ' , 



CaO 6-01 6-14 -109 = 1 



U0 3 6014 61-37 '213 = 1-95 



SiO„ 18-55 18-93 -315 = 2*88 



HO" 13-28 13-56 -753 = 6*90 



97-98 100 



I. Analysis of uranophane from Stone Mountain, Georgia, from 

 which the small percentages of A1 2 3 , Fe 2 3 , MgO and 

 P 2 5 are omitted. 

 II. Analysis I recalculated to a basis of 100. 

 III. Molecular ratios of II. 



The molecular proportions given under column III corre- 

 spond to the formula CaO-2U0 3 -3Si0 2 -f-7H 2 0, which indicates 

 one part more of Si0 2 and PJ 2 than is required by the formula 

 for uranophane, CaO-2U0 3 -2Si0 2 + 6ET 2 0. The discrepancy in 

 these two constituents is easily accounted for, however. The 

 Si0 2 is increased by the presence of finely divided mineral 

 particles from the granite and hyalite, it being quite impossible to 

 effect a complete separation of the uranophane from these two. 

 The amount of available material was so small that it was 

 impossible to separately determine the combined and uncom- 

 bined water, and under the total water given in the analysis, 

 it is reasonable, at least, to assume that a small fraction of it is 

 hygroscopic (uncombined) water. What now appears then as 

 a slight variation from the exact formula for uranophane, dis- 

 appears when the above facts are considered. 



A comparison of the above analysis of the Georgia mineral 

 with several by Genth and von Foullon of the uranophane 

 from Mitchell County, North Carolina, and one from Kupfer- 

 berg, Silesia, quoted by Dana,* shows very close agreement. 

 The reported occurrence of uranophane in granite at Kupfer- 

 berg in Silesia appears in this particular to be similar to that, 

 in Georgia. 



Geological Laboratory of Denison University, 

 Granville, Ohio. 



* Op. cit. 



