CALIFORNIA ACADEMY OF SCIENCES. 359 



Fig. 1, Plate I, represents en face the crystal upon which 

 G ( — 7 P) was observed. On the same crystal, an extremely 

 minute triangular face C is also observable in the angle of b, t, 

 and n. Reflections could be obtained from it only with the lens 

 thrown in front of the telescope of the goniometer, and even 

 then it was found desirable to remove the signal and illuminate 

 directly from the strong lamp-flame. In this way it seemed clear 

 that the face lay in or very close to the zone n. b. c; six readings 

 varied from 87° 5' to 87° 59', the mean being 87 c 33'. With 

 this reading and 49° 45' obtained from b, the symbol was calcu- 

 lated to be — -y- P 10. The observed angles of C to the other 

 faces in the zone b . c, agree almost exactly with the calculated 

 values, regarding C = — % 1 - P 10. Considering, however, the 

 inevitable error in taking readings after such a fashion from so 

 minute a face, I would prefer to adopt provisionally the simpler 

 symbol — 10 P 10, until further more exact observations become 

 possible. The face is considerably enlarged in the drawing. 



Figs. 2 and 2 a represent a front view, and Fig. 3 a side view 

 of a crystal previously described* with the face W (3 P oo) 

 largely developed. This crystal was broken from a large geode 

 completely lined with similar forms. Jt is the only specimen 

 among those from Calico District that presents crystals upon 

 which even a trace of "W is to be observed. It will be seen later 

 that this face is the most important one on nearly all the Death 

 Valley specimens recentty examined. It is possible that a 

 mistake has been made concerning the locality of the geode, 

 and that it really comes from Death Valley. 



Fig. 4, PI. I, shows en face an interesting combination of 

 faces, thus far observed on but a single medium sized columnar 

 fragment from a large geode. There are present g (o P), b ( — P), 

 Jfc(-3P3),s (oo P), t (oo P 2), n (oo P oo), / (— 2 P oo), and 

 the three new faces D, <P, and p. The faces g, b, s, and k are all 

 in good condition. The two faces of k ( — 3 P 3) have attained 

 a size and brilliancy observed on no other crystal. From fault- 

 less reflections, the angle k : k was found equal to 157° 53' 18" 

 (calculated 158° 0' 24"). X (— 2 P oo) and n (oo P oo] are 

 very small but brilliant, while /, D, 0, and p are so minute and 



* 1. c. p. 32. 



