108 CONTRIBUTIONS TO MINERALOGY. [bull. 262. 
The brachypinacoid is present on four crystals, usually as broad 
faces. Some give relatively good reflections. 
The macropinacoid occurs on all crystals, except the one from Ari- 
zona, and always as narrow faces. The reflections were poor, but 
serve to identify the form. The <j> angles measured are as follows: 
Measured. 
Cal 
iulated. 
California 
o 
90 
93 
90 
92 
91 
90 
/ 
02 
46 
00 
57 
15 
16 
o / 
Do 
Do 
New York 
90 00 
Do 
Do 
The brachv prism /=oo 2 = 120 occurs on four crystals as narrow 
faces giving- fair reflections. 
Measured. 
Calculated. 
California 
o 
30 
28 
29 
29 
29 
00 
00 
22 
?A 
89 
O 1 
Do „ 
Do 
> 29 20 
New York 
Do 
The unit prism is poorly developed on the California crystals, 
being present but once as a narrow face giving a poor reflection. On 
the Arizona crystal it occurs twice as broad faces. 
Measured. 
Calculated. 
California 
o / or 
48 52 ^ 
Arizona .. 
49 16 
J- 48 20 
