278 



C. ANDERSON. 



forms. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 



v (201) v v 

 h (221) h h 



•(HI) 



P(223) 



A; (221) k k 



7(121) 



R (241) R R 

 X(481) X X 

 A(2-18-3) A A 



V V V V 



h h h h 



s ... s ... 



p ... p ... 



k k k k 

 y y ... 



k 



V 



h 

 k 



V 



h 



s 



p 



k 



V 



h 



V 



h 



V 



h 



V 



h 



V 



V V V 



h h h 

 s s s 

 P ... P 

 k k k 



y 



V 



h 



k 



P 



k 



k 



k 



k 



k 

 7 



R R R R 



... XX X 



... AAA 



R 



R 

 X 



R 



R 



R 

 X 



R 



R 





I 



R R R 























In the above list Nos. 1 and 2 are from specimen A, Nos. 

 3 to 6 from B, Nos. 7 to 18 from C, and it will be observed 

 that A does not occur on the crystals of O, also that the 

 new form X is commoner on specimen A and B; otherwise 

 the combinations are very similar for all the crystals. 



Neiv form X (481). — This was found on seven crystals 

 and its indices were determined from the following measure- 

 ments; in most cases the reducing objective was used as 

 the faces are small. 



Crystal. 



Signal. 



1 



good 



2 



fair 



4 



good 



5 



fair 



8 



fair 



(3 



<£ 



P } 







__ o / 



/ 







30 21 



83 10 



Average. 



Calculated 



30 12 



82 57 



_ / 



_ / 







, 6 30 6 



30 1 



30 15 



83 5 











p 83 2 



83 2 



30 



83 5 







30 3 



82 49 







"29 43 



83 4 







The form occurs as a minute line face or a spot between 

 w (120) and R (241); although it is small, the signals are 

 distinct, and the form may be considered as established 

 beyond doubt. 



Doubtful forms. — In all the crystals there is a much 

 striated area between c (001) and (101) which gives a 

 succession of overlapping signals. No forms can be 

 definitely established here, but /* (105) and D (104) are 



