Chemical Examination of Fahhmite. 69 



1 1 atoms silicate of alumina, _ _ _ 46*75 



5 atoms silicate of lime, - - - - 27 5 



2 atoms bisilicate of soda, - - - - 16'0 



1 atom silicate of iron, ----- 6-5 



9G-75 



Were we to consider the bisilicate of soda, and silicate of 

 iron to be accidental ingredients, the constitution of the mine- 

 ral would approach very nearly to that of common scapolite. 



24. FAHLUNITE, OR TRICLASITE. 



Two different substances have been distinguished by the 

 name fahlunite, or triclasite. One analyzed by Hisinger,* 

 which seems to be the same with the Gieseckite of Strorneyer, 

 It has a blackish-green color, and nearly the same specific 

 gravity as the hard fahlunite. But it contains 13*5 per cent 

 of water. The other substance has been usually called hard 

 fahlunite, from its greater hardness. It was analyzed in 1815 

 by Hisinger, and 1B21 by Strorneyer. The following table 

 exhibits the constituents of this mineral, according to the 

 analyses of these chemists. 



* Afhandlingar, vi. 210. 



t Hisinger, Afhandlingar, iv. 342. 



t Strorneyer, Unlersuchungen, p. 553. 



