284 Dr. J. E. Reynolds on certain Mineral Silicates. 



v Si/ 



Pyroxene . . . 2 X° 



/0 2 \ 



Rhodonite 



Amphibole 



Anthophyllite 



\Bi/ 



Mn'Yo 



/o 2 \ 



/0 2 \ 



\Si/ 



. ( f Mg-}-iFe)"Vo 



/0 2 \ 



Class 2. 



\Si/ 



iEgirite . . aR -HFe)X° 3 

 /0 6 \ 



= SiO||0 2 || (i(Na 2 ,R) + i/3Fe) (Dana). 



\Si/ 



Acmite . (^Re+|F e )Vo 3 



/0 6 \ 



\Si/ 



Babingtonite (|R n +pV)X 03 



\Si/ 

 Beryl . . QBe" 3 4-fAl)X° 3 



/o 6 \ 



Pollucite 



\ Si/ 



(Cs 6 +Al)X0 3 

 /O a \ 



Spodumene . (£R 6 +fAl)X° 3 



Class 3. 



Si 2 . 



Petalite . . (£R6+4 A1) \/o 3 

 /0 12 \ 



The last is the only member of Class 3 occurring- in this divi- 

 sion. The relation of petalite to spodumene and other members 

 of the section is thus clearly shown by the formulae. 



