140 



TRAVIS— PYRITE FROM CORNWALL. 



[June 22 



surface. This rounding off was often noticed on (13.7.3) ^^^^ not 

 on (952). 



Crystal 11 shows a rare combination of forms. It diverges 

 remarkably from the type, and indeed might have been supposed to 

 come from another locaHty, were it not for the perfectly typical 

 markings on the pyritohedron and octahedron. Again, one of the 

 forms it shows, (542), is found on crystals 6 and 15, which are per- 

 fectly typical in all respects. It is a rough fragment 1.5 cm. long, 

 showing on one end an octahedron face with two adjacent (221) 

 faces, and one face each of (321), (542), (14.11.8), (432), (14.7.3). 

 A rough curved, irregular surface breaks the (iii, 210) zone beyond 

 (321) for tlie space of 2 mm. ; (521) and (210) appear beyond this 

 irregular portion. The octahedron and (221) faces are each a 

 couple of mm. in extent; the face of (321) is i mm. each way, and 



•/^2 



/// 



^32' 774'»'^'^3 



32/ * V52v.^r^ 

 ' * ./3.7.3 

 'S2' ,. 

 S3/ /^^^ 



02/ 



\0^ 



^2/^^/3.7.3 33 /'''^■'^•'^ 



7S2' 



2/0 



Fig. s. Type I. 



Gnomonic projection on plane of octahedron. Illustrating 

 zonal relations. 



the (14.7.3) ^^d (531) faces are 0.5 mm. wide; (14.11.8) and (542) 

 are about 0.3 mm. wide, and (432) about o.i mm. If the pyrito- 

 hedron be regarded as (102), the observed faces have the positions, 

 (102), (III), (212), (122), (315), (213), (324), (11.8.14), (425), 

 and (9.3.14). Fig. 3 shows the combination of forms observed on 

 this crystal. 



