1877.] 



511 



[KOnig. 



8.256 



\ 3.147 



99.91 

 The oxygen ratio becomes : 



ii : ipfc 



32 : 3 



R 



11 



H . 



4 . 



(H,0)^ [(Si Ti Zr) O,] ^^ [(Fe, Al,) O.] [(Fe, K, Mu, Na.) o] 



To obtain the atomistic symbol, we have : 



Quotients. 

 16.195 

 9.281 

 5.090 

 20.331 

 2.696 

 4.159 

 1.885 



Si 



Ti 



Fe 



Fe 



Mn 



K 



Na 



H 



O 



= 38.060 



28 

 50 

 112 

 56 

 55 

 39 

 23 

 1 

 16 



0.578 

 0.185 

 0.044 

 0.363 

 0.049 

 0.107 

 0.081 

 0.393 

 2.379 



Atoms. 



13.13 

 4.25 

 1.00 

 8.25 

 1.11 

 2.43 

 1.84 

 8.93 



54.07 



The most rational approach to these figures will be represented by the 

 symbol 



by which all the affinities are satisfied. 



Note. — In the above calculation zirconium is converted into its equiva- 

 lent of titanium, aluminum into ferric iron, magnesium and copper into the 

 bivalent ferrous iron. Tantalic acid was left out, partly because its exist- 

 ence in the mineral is not established beyond doubt, and also because the 

 general features of the formula would not be altered by its introduction. 



Comparing my analytical results with those of Pisani, Scheerer, et. al., 

 who analysed the Brevig mineral (Dana, mineralogy, ed. 5, 309), whilst a 

 general conformity appears evident, there exists a diflerence in the percent- 

 ages of titanium, aluminum and manganese too great to be passed in 



