115 



substance has been deposited upon the original feldspar crystals 

 and in parallel orientation with reference to them. The zlnn- 

 waldite also proves to be later than the elpidite. On the other 

 hand, parisite, cordylite, ancylite and yttriumapatite are all of 

 later origin than the zinnwaldlte. 



25. Taiiiiolite. 



The investigation of this mineral has been attended with 

 considerable difficulty, and the results obtained are such that 

 the mineral cannot be said to be fully determined. This is 

 especially the case as regards its chemical composition, because 

 for want of a sufficient quantity of pure material a complete 

 analysis could not be made. The material was also not 

 altogether suitable for crystallographic examination , and for 

 the results obtained no high degree of accuracy can be 

 claimed. 



Already when I observed this mineral on Narsarsuk for 

 the first time, I clearly saw that it must be a mica, though 

 the crystals had a habit that had not before been observed in 

 any species of mica. This view was confirmed by the angular 

 measurements which I made afterwards ; though they could not 

 be made with great accuracy, yet they showed that all of the 

 forms present corresponded to known forms on other minerals 

 of the mica group. And when at last the blowpipe examination 

 of the mineral proved that it contained a considerable amount 

 of lithia, there seemed to be sufficient reason for considering 

 it as a variety of polylithionite M. Only after prolonged and 

 laborious efï'orts could a small amount of pure material be ob- 

 tained, on which an analysis was undertaken. Though this 

 analysis could not be made complete, it fully showed that the 



^) Figs. 9 and 10 on Plate III are there denoted as «polylithionite», which 

 should be altered to «tainiolite». 



