514 PROCEEDINGS OF THE NATIONAL MUSEUM. vcr,. :>!>. 



P (332) was seen several times as a brilliant though narrow face. 

 Its best development was on crystal BlO, which is illustrated in 

 figure 23. The angles are: 



(332) Measured <p = 57° 27' P = 73° 22' 



Calculated ^> = 57° 35' p = 74° 14' 



A= 0° 08' A = 0° 52' 



This form was described as new from Westfield by Gorgey and 

 Goldschmidt. 



$ (546), described as new on Westfield datolite by Ungemach, was 

 observed as two rounded faces on crystal BlO, shown in figure 23. 

 It was also seen as two small and dull faces on crystal 7. The signals 

 from the faces were very poor. Angles : 



(546) Measured, maximum <p = 6l° 18' 



Measured, minimum (p = 60° 57' 



Measured, average <p = 61° 07' 



Calculated ^ = 63° 04' 



A = 1°57' 



t) (811). The form I) (911) was described as new on datolite from 

 Westfield by Gorgey and Goldschmidt. Ungemach described t) (811) 

 as occurring on the crystals examined by him and suggested that 

 the form (911) of Goldschmidt and Gorgey was the same. The form 

 was seen on crystal BlO, illustrated in figure 23, and also as small 

 dull faces on crystal 7. The angles are: 



Measured <p = 85° 00' p = 86° 05' 

 (811) Calculated <? = 85° 28' p = S6° 26' 

 (911) Calculated ^ = 85° 58' p = 86° 49' 



The measured angles would seem to indicate the form (811), although 

 both forms probably occur. 



RELATIVE IMPORTANCE OF FORMS. 



The forms found on the Westfield datolite may be grouped accord- 

 ing to their relative importance as follows : 



1. Forms practically always present as large and important faces: 

 a (100), rrw (011), g (012), x (102), e (T12). 



2. Forms practically always present as smaller faces but sometimes 

 large: b (010), c (001), m (110), n (111), M (T14), X (113). 



3. Forms frequently present as small faces: t (013), v (103), u (104), 

 o (120), r (230), a (014), /3 (121), Q (122), U (123), v (Til), b (223), 

 i (123), a (T24), tt (231). 



