238 



BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



BLAINE COUNTY 



The best specimens of aragonite which have been seen from the 

 State were collected by D. F. Hewett, of the United States Geological 

 Survey, from a prospect on the west bank of Wood River between 

 Bellevue and Hailey, a little north of the mouth of Mammoth Gulch. 

 The aragonite crystals, which are transparent and colorless and 

 average 2-3 mm. in length, occur implanted in cavities in spongy 

 limonite. So far as could be determined these are untwinned. The 

 habit is peculiar and, if the interpretation adopted is correct, they 

 exhibit an odd symmetry and have several planes new for the species. 



49 50 51 



Figs. 49-51.— Aragonite. Wood River district, Blaine County 



Crystal 1, illustrated in Figure 49, is typical of the crystals of the 

 specimen and shows the lack of symmetrical representation of the 

 terminal planes. The determining faces of the elongation are the 

 very steep pyramid G (10.10.1) and the orthodome 77 (0.24.1). The 

 termination shows two faces of the dome i(021) and only one of 

 d(l02) while there are two faces in front of o(112) with no corre- 

 sponding back faces. There is one face giving the indices (152) and 

 one giving (413). The angles measured/on this crvstal are as follows : 



