ISO.MKTHK' SYSTKM 



na : a : ma 



Forms 

 Tetartohedral pentagonal dodecahedron; R, L 



KTT(hkl). KTT(hkl), KIT (khi), KIT (khi). 



The >\ -mincl ry of the type requires but one quarter of the faces 

 of the holosymmetric form. Figure 107 represents the poles of 

 the -f right tetartohcdr.-il pentagonal dodecahedron. The form 

 is bounded by 12 irregular pentagonal faces, three of which are 

 grouped around the trigonal axes: the digonal axes bisect an edge. 



4L 



-(-B 

 -L 



-L 



+B 



-R +L 



Fio. 107. The Plus Right *(?* 

 rahedral Pentagonal Dodooa 



FIG. 108. 



Figure 108 represents the 8 faces of the hexoctahedron grouped 

 around the ditetragonal axis, which axis in the tetartohedral class 

 is a digonal axis. Four tetartohedral pentagonal dodecahedra 

 arc possible. If the two faces + R are extended, the + right, 



li<;. 109. The Plus Right 

 Ti'tartohodral Pentagonal 

 Dodecahedron, Kir(hkl). 



Fu;. 110. The Plus Left Te- 

 tartohedral Pentagonal Do- 

 decahedron, irK(khl). 



Fig. 109, pentagonal dodecahedron results ; if + L are extended, 

 the + left, Fig. 110 ; -- R is the negative right, L the negative 

 left forms. rights are congruent, for if the face + R is revolved 



