422 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 59. 



i— — 10 (101). Observed in several cases as a dull face yielding no 

 signal but measured by the position of maximum illumination. 



<t> p 



Measured 90° 00' 32° 10' 



Calculated 90° 00' 32° 35' 



d=+2 (221). Often 

 present as narrow to line 

 faces on both types of 

 crystals. 



P 



33° 15' 70° 08' 

 33° 09' 70° 09' 



Fig. 2.— Creedite crystal. Type II. 



Measured . . 

 Calculated . 



p= +1(111). Thisisthe 

 most prominent pyramid 

 face and is generally bright, 

 yielding excellent reflec- 

 tions. In the second type 

 of crystal it reduces the 

 negative pyramid to small 

 faces. 



4> p 



Measured.. 34° 29' 54° 36' 

 Calculated. 34° 30' 54° 36' 



»«.-l (Til). This face 

 is the same size as p in the 

 first type of crystal, but is 

 small on the second. It is 

 bright and yields excellent 

 reflection. 



Measured 28° 52' 52° 57' 



Calculated 28° 52' 52° 56' 



The elements and calculated angles are brought together in the 

 table given below. 



Creedite.— Monoclinic. 



