458 H. W. Foots — Occurrence of Pollucite, 



rill while mining for gem tourmalines. A full description of 

 this occurrence together with an analysis and a discussion of 

 the chemical composition of the mineral has been given by 

 Prof. H. L. Wells.* The material at Hebron was all found 

 as loose pieces in two cavities, while at Rumford, which 

 is about thirty miles north of Hebron, it is found intimately 

 associated with quartz, albite, muscovite, tourmaline, lepidolite 

 and spodumene. The specimens are not very attractive in 

 appearance as neither the pollucite nor the associated minerals, 

 with the exception of tourmaline, occur well crystallized. 

 The irregular masses of pollucite are sometimes quite large, so 

 that, for example, for a distance of ten centimeters there will 

 be continuous pollucite. Small particles of the mineral are 

 colorless and perfectly transparent, but the masses look as if 

 they had been crushed and the appearance is therefore white. 

 The quartz at the locality is mostly smoky so that it is readily 

 told from the pollucite at a glance, but some of it is quite 

 white, and then it is almost impossible without physical or 

 chemical tests to distinguish the two minerals apart. A 

 great deal of credit is due to Mr. Bailey for having ob- 

 served that the pollucite was something different from quartz, 

 which needed investigation. 



Although occurring in masses of considerable size, the 

 pollucite is not very abundant, but it is hoped, now that the 

 mineral has been identified, that it will be more carefully 

 looked for and saved. It is possible and even quite probable 

 that pollucite is not at all a rare mineral at the tourmaline 

 and lepidolite localities in Maine, but has been overlooked as 

 it resembles quartz so closely and does not occur in character- 

 istic crystals. 



Material for a chemical analysis was separated in a very 

 pure condition by means of the potassium mercuric iodide 

 solution. That which was used for the analysis ranged in 

 specific gravity between 3*029 and 2*938, a difference of 0*091. 

 Wells gives 2*986 and 2*976 for the mineral from Hebron. 

 The method of analysis was as follows : 



The substance was digested with strong hydrochloric acid 

 for several hours until completely decomposed. The silica 

 and alumnia were then determined in the usual manner. 

 The filtrate from the alumnia precipitation was evaporated 

 to dryness and ammonium salts driven off with extreme 

 caution. The chlorides of the alkalies were dissolved in very 

 little hydrochloric acid and enough lead chloride added to 

 combine with all the caesium to form the salt Cs 2 PbCl 6 .f 

 Chlorine was then passed into the hot solution which wa&- 



*This Jour. III. xli, p. 213, 1891. 

 f Ibid., xlvi, p. 186, 1893. 



