

CLEAVAGE. 



Fig. 91. 





If the rhombic dodecahedron, fig. 91, be cleaved 

 parallel to the planes, , 6, c, d, and to the four 

 planes opposite to these, until the four remaining 

 planes of the dodecahedron disappear, an obtuse octa- 

 hedron will be produced. 



Fig. 92. 



Fig. 92 exhibits this octahedron separately, the 

 planes being marked by the same letters as appear 

 on the corresponding planes of the dodecahedron. 



Fig. 93. 





If the cleavage be effected parallel only to the 

 planes 0, d, e, and 7z, b, k 9 until the other primary 

 planes disappear, an obtuse rhomboid will result, as 

 seen in fig. 93; this rhomboid measures 120 over 

 the edges at which the planes #, and e, meet. 



