Spodumene and its Alterations. 335 

 H 2 R« W Si 12 O 37 or H 2 (H, Na, K) 6 Al 6 Si 12 0" 

 « j Na' Si 3 ) , , 



This yields the following calculation for the theoretical per- 

 centages in the constitution of the mineral. 



]2 Si 336 ") Calculated. Found. 



6 Al 163.8 I f Silica 58.46 58.70 



6 ISTa 138. J- equivalent to j Alumina 24.99 24.55 



2 H 2. | } Soda 15.09 | , fi qi 



37 592, J t Water 1.46 j" 1D,,5i 



1231.8 100. 99.56 



In view of the results obtained by so careful an analyst as 

 Prof. Burton, and of the fact that his analysis and formula have 

 been for over ten years associated with the name "Cymatolite," 

 it seemed to me at first most judicious to attach a new name* to 

 the new constitution of my own abundant material. However, 

 since I have received from Prof. Shepard a fragment from an 

 original specimen of his own collection, its identity with mine in 

 all physical characteristics, seems to justify the application of 

 the name, Cymatolite, to my own material as well. And yet it 

 may be convenient to retain the name I proposed, Aglaite, 

 (from dylabg, brilliant) for the Barrus farm variety of Cyma- 

 tolite. As already explained, this differs from the rest, both in 

 the constitution of the protoxides, and in possessing a more 

 brilliant silvery-white lustre and color, and generally a flat mi- 

 caceous instead of a "wave-like" structure — a variety, therefore, 

 to which the etymology of the name, Cymatolite, is not appro- 

 priate. 



Cymatolite appears to be a hydrous bisilicate, which, excluding 

 all but basic hydrogen, possesses the essential constitution of 

 Spodumene. The character of the alteration may be simply 

 stated. 



In 3 molecules of Spodumene, the monad element has been 



* Engineering and Mining Journal, April 7, 1877. 



