64 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 



FIGUKE 17. Penetration twin on (023). Forms: c{001>, 6{010>, a{100}, m{110}, Z{210}. 



FIGURE 18. Penetration twin on (023). Forms: c<001>, ft{010>, a{lOO}, m{110>, ?{210>. 

 c 



.-b 



FIGURE 19. Crystal 29, showing rare form p. FIGURE 20. Crystal 32. Forms: c<001>, 6{010}, 

 Forms: c{001>,6<010},o{100>,Z{210},p{214}. a{100>, m{lW}, l{210}, 



FIGURE 21. Crystal 33. Wedge-shaped crystal with unequal development of the faces of /. Forms: 

 c{001>, 6<010>, o{100>, m{110>, 



