Watson — Occurrence of Uranophane in Georgia. 465 



color, the former predominating, and forms an irregular coat- 

 ing not exceeding one-eighth to one-sixteenth of an inch in 

 thickness, usually less. It is tipped or coated with the clear, 

 colorless, and transparent, drop-like forms of the mineral hyalite. 

 The two minerals are so intimately associated that it is almost 

 impossible to effect a complete separation of them. 



The Stone Mountain granite, with which the uranophane is 

 associated, is a light gray, medium-grained, biotite-bearing 

 muscovite granite, composed of quartz, orthoclase, microcline 

 and soda-lime (oligoclase) feldspar, muscovite and biotite, with 

 sporadic microscopic accessories. Fresh specimens of the 

 granite were analyzed by Packard in the Survey laboratory 

 with the following results : 



' SiO„ _ 72-56 



A1 2 3 1 14-81 



FeO .£ 0-84 



CaO 1-19 



MgO 0-20 



Na 2 . 4-94 



K 2 5-30 



H 2 (ignition) „ 0*70 



Total 100-54 



Several tests were made by the writer on separate portions 

 of the granite for the presence of uranium, with negative 

 results. The yellow powder gave the usual tests before the 

 blowpipe for uranophane. Packard carefully separated, by 

 means of a lens, a small amount of the yellow mineral from 

 particles of the granite and other possible impurities for chem- 

 ical analysis. 0*1310 gram of the powder was used, which 

 gave : 



Si0 2 18-55 



U(ITQ 4 ) 2 47-18 



(U0 2 ) 2 , Fe 2 3 ,P 2 5 ._ 4-95 



A1 2 3 6-33 



CaO 6-64 



MgO 1-98 



H 2 (ignition) 13*28 



Total 98-91 



As Packard remarks, the above result clearly indicates that 

 the material was not entirely free from impurities. A second 

 weighed portion was accordingly selected amounting to 0*5120 

 gram of the dull lemon- or sulphur-yellow mineral and treated 

 with HNO s , which after digestion left a residue weighing 

 0*24:60 gram, yielding 0*2660 gram for analysis. This gave": 



Am. Jour. Sci.— Fourth Series, Yol. XIII, No. 18.— June, 1902. 

 32 



