THE MINERALS OF IDAHO 



81 



In rich ore from the No. 4 tunnel of the Mountain Chief mine, Quartz- 

 burg district, it occurs as small grains and prisms showing brilliant 

 cleavage scattered through quartz which con- 

 tains large pale fragile crystals of pyrite. The 

 mineral also occurs in the form of minute 

 prisms in small cavities between quartz crys- 

 tals, some of which are bent and curved like 

 stibnite crystals. The mineral closely resembles 

 galenobismutite from the Belzazzar mine in the 

 same area but before the blowpipe it gave quali- 

 tative reactions only for bismuth and sulphur 

 with no lead. A pure sample separated with 

 heavy solutions and partially analyzed gave 

 0.60 per cent of lead and no copper. A crystal 

 selected from one of the cavities of the speci- 

 men gave approximate measurements indicating 

 the angles of bismuthinite but with 3 forms 

 apparently new for this species. The angles 

 are given in the following table while the habit 

 and development of the crystal are shown in 

 Figure 1. The letters used to designate the 

 supposedly new forms are those assigned to the 

 corresponding planes on stibnite. The dif- 

 ferences between measured and calculated 

 angles is due to the poor signals produced by 

 the etched and striated faces. 



Fig. 1. — Bismuthinite. 

 Crystal from Moun- 

 tain Chief mine, Boise 

 County, showing new 

 FORMS (210), (023), AND (103) 



Forms and angles on bismuthinite from Boise County 



At the Gold Hill mine near Quartzburg bismuthinite frequently 

 occurs as bunches of columnar or fibrous steel gray material in quartz 

 gold ore. It always contains native gold. 41 



41 Waldemar Lindgren. Oral communication, May, 1921. 



