THE MINERALS OF IDAHO 



243 



The interpretation of such a twin is difficult, for example the face 

 indicated on the figure by the letter b 2 may in fact be an extension 

 of m 1 and similar alternatives exist for all of the prismatic faces. 

 Time was not available for further study of the results on this crystal, 

 but it is possible that a different interpretation might be found 



Ubi: 



771. 



53 

 Tigs. 53-54.-53, Cerusite. Independence mine, Blaine County. Vertically elongated twin on 

 7n(110). 54, Cerusite. Same. Twin simulating quartz crystal 



preferable. The results as given, identify the forms and establish 

 the twinning plane as m(110). They also serve to explain the 

 hexagonal aspect of the examples like that illustrated in Figure 54, 

 which is another case of the same twinning but without reentrant 

 angles. 



