356 Palache and Wood — Crystallographic Study of Millerite. 



Besides the signals reflected from faces of these forms which 

 are more or less well established, there were read, in the prism 

 zone, signals reflected from faces in thirty-two positions 

 (reduced to the positive sextant) which corresponded more or 

 less well to prisms of complex indices. For the most part 

 only one face of each of these forms was seen, and the signals 

 were generally of very poor quality. These facts together 

 with the complexity of the indices deduced, and the certainty 

 of the occurrence of oscillation-vicinals whose signals corre- 

 spond to no prism however complex, render the establishment 

 of any of them very doubtful. Therefore all are rejected and 

 none of the data is published. 



Doubtful Rhomb ohedrons. 



t, (0331). This rhombohedron was reported by Miller on 

 the strength of a contact measurement on a rough terminated 

 crystal. We can not confirm the form, but one face on one 

 crystal was found approximating to its position. 



Crystal. Signal. Headings. 



P 



24 very poor 30° 00' 48° 56' 



Calculated 30° 00' 48° 36' 



A, (3031). This rhombohedron is new and very doubtful, 

 relying for its establishment on two measurements on two 

 different crystals. 



Crystal. Signal. Eeadings. 



(j> p 



30° 00' 48° 42' 



150° 00' 48° 10' 



30° 00' 48° 26' 



30° 48° 36' 



The form is therefore certainly indicated, but by no means 

 established. 



x, (4041). This form also is new and rests on a single 

 measurement whose signal was of fair quality. The measured 

 value for p was 56° 34/ ; the calculated value of p is = 56° 

 31 '4:9" ; apparently the form only lacks the finding of more 

 faces to_establish it. 



j, (5051). One face only supports this form. 



Crystal. Signal. Eeadings. 



<t> p 



23 poor 29°'46' 62° 26' 



Calculated 30° 00' 62° 07' 



I, (0991). Only one face of this form was found. This 

 gave a fair signal showing a definite face. 



23 

 24 



very poor 

 faii- 



Mean 

 Calculated 



poor 



