216 H. L. Wells — Composition of Pollucite and its 

 This analysis is given below : 





Hammelsberg, 





Ratio from the 





New 



analysis. 





mean of 4. 





I. 



II. 



III? 



' 



SiO s 



46-48 











•775 or 4-58 or 916 



Al.O, 







17-24 







•169 or 1-00 or 2'00 



Cs,0 







30-71 



30-53 



•109 ) 



K s O 







0-78 



0-41 



•006 [■•151 or 0-89 or 1'78 



Na 2 





2-31 



2-19 



•036 ) 



H,0 



2-32 











'129 or 0-76 or 1-52 



3-30 



He does not publish any ratio with this analysis, but says : 

 " These results confirm the former." The emphasis is Rain- 

 melsberg's. It may be noticed, however, that this analysis 

 corresponds very closely to the formula, 9Si0 2 . 2Al a O, . 2R' 2 . 

 1JH 2 0, or, putting in H with R/, it corresponds very well 

 with the metasilicate formula, R\ Al 4 (Si0 3 ) 9 . Moreover the 

 formulae just mentioned correspond much better with the 

 analyses of Plattner and Pisani than Rammelsberg's formula 

 does. What the probable formula for pollucite is, will be dis- 

 cussed after giving the analysis of the Hebron mineral. 



The locality, Hebron, from which the new material comes, 

 furnished the lepidolite from which Allen * extracted a large 

 quantity of caesium and rubidium, the material used by John- 

 son and Allenf in determining the atomic weight of caesium 

 as now accepted. Hebron also furnished the remarkable beryl 

 in which Penfield:}; found 2*92 per cent of caesium oxide. It 

 might have been expected, therefore, that this locality would 

 be likely to furnish pollucite ; indeed, Professor Brush tells 

 me that he has tested a large quantity of quartz fragments 

 from the locality, hoping that some of them might be this 

 mineral. 



The specimens were found during the past summer by Mr. 

 Loren B. Merrill, of Paris, Me., and a few pieces were sent by 

 him for identification to Professor Brush, who very kindly 

 gave them to the author for examination. Mr. Merrill has 

 since very generously loaned us his whole stock of the mineral, 

 amounting to more than half a kilogram, in order that a 

 thorough examination might be made. The mineral is said by 

 the discoverer to have been found in cavities. § It was associ- 



* This Jour., II, xxxiv, 367. \ This Jour., II, xxiv, 94. 



X This Jour., Ill, xxviii, 29. 



§ Mr. Merrill says, in a letter received after this article was in print, that the 

 pollucite was found in only two cavities. In one of these only two or three pieces 

 were found, associated with large, etched quartz crystals. In the other cavity the 

 main part of the mineral was found in a loose heap mixed with clay. This last 

 cavity was open at the top, and was 3 feet wide 6 feet long and 18 inches deep. 



