1906] 



TRAVIS— PYRITE FROM CORNWALL. 147 



shows the cube (100) with its adjacent pyritohedron faces (210) 

 and (210), and (001) with (102). There are two octahedron faces, 

 (ill) and (ill). The former face, which is surrounded by the 

 zones containing the new diploids, would have been 3 mm. on a side, 

 but another smaller crystal has grown into it, leaving only two 

 corners. Of the three zones of diploids that surround ( 1 1 1 ) , one has 

 two faces in it, (11.8.5) and (321); the second three, (876) 

 ( 1 1.8.5) ; and the third two, (753) and (321). The (876) and (753) 

 faces are about 0.7 mm. wide, and the (i 1.8.5) face in the second 

 zone is i mm. wide. All are perfect faces. The (i 1.8.5) zone is 

 good at one end, but at the other runs off into a broken vicinal face. 

 At its good end is a face of (211), about i mm. long. Between this 

 latter and the (11.8.5) and (321) faces lie the trisoctahedrons (221) 

 and (774) described above. 



>/oz 



<?2/. 



•m. 



77^ 



^ aS^-ff^j'^ '22/ 



753 

 *32/ 



5S2 



, 2JO 



Fig. 10. Type IL Gnomonic projection on plane of octahedron. Illustrating 



zonal relations. 



Zonal Relations of Type IL 

 The most important zone in this type, outside of the cube- 

 pyritohedron zone, is that of the octahedron and pyritohedron, sym- 

 bol (121). This affords all the observed diploids, seven in number, 

 one of which (321) is practically always present. The trisocta- 



