AXIAL ELEMENTS. 

 Lift of crystals by localities. 



43 



a S, simple crystal; G, group of crystals in nearly parallel position; T, twin crystal. 



AXIAL ELEMENTS. 



The discussion of the axial elements of ferberite leads at once to the 

 question of the relation of ferberite to the wolframite group. 



In this connection a consideration of the relation in angular values 

 between the pure iron tungstate and the pure manganese tungstate 

 is of interest. The ferberite crystals at hand did not yield results as 

 satisfactory as had been expected, because of the imperfection of the 

 crystals, due to striations, parallel groupings, and like features; 

 because of the scarcity of well-developed terminal forms ; and because 

 the high polish of most of the crystals had been destroyed by the 

 hydrofluoric acid used to remove the matrix and clean the crystals. 



CALCULATION OF VALUES. 



Below are given the best measurements obtained that are suitable 

 for the calculation of the axial elements, and these are compared with 

 the measurements given in the literature for the members of the 



