470 E. V. Shan7ion — Famatinite from Ooldfield^ Nevada. 



Goldfield crystal are compared with the observed angles 

 of enargite. The close agreement with enargite in the 

 prism angles is shown below. 



Observed, famatinite enargite (Dana) 



x:^" 60° 24' 60° 17' 



li'.li' 59° 12' 59° 43' 



This will serve to show the orientation of the crystal 

 and to indicate that the famatinite from the Goldfield 

 district is isomorphons with enargite and the value for 



A- 



X. 



the a axis does not differ greatly from that of enargite. 

 With this known orientation the domes observed were 

 plotted on a stereographic projection and gave the 

 indices (104) and (025). The reflections obtained from 

 these faces were poor and the angles obtained were not 

 considered sufficiently trustworthy to serve as a basis 

 for calculating a value for the c axis. Both in the pro- 

 jection and in the accompanying drawing the axial ratios 

 of enargite were used. The figure reproduces the form 

 and appearance of the crystals. The locality is not 

 given more nearly than one of the mines of the Goldfield 

 Consolidated Co. 



The base upon which the crystals, described above, are 

 implanted is similar to the majority of specimens in the 

 lot received. It consists of fine-grained, pinkish gray 

 famatinite. "When polished and examined under the 

 reflecting microscope, the distinctly pink mineral is seen 

 to contain graphic inclusions of a silver-white mineral 

 which in its microchemical reactions agrees with bis- 

 muthinite. The ore reacts for bismuth but not for tel- 

 lurium. The pink mineral contains both arsenic and 

 antimony, the antimony preponderating. One of the 

 samples consists of a fine clayey gouge containing finely 

 triturated native tellurium. Nothing was observed in 

 the specimens which seemed to correspond to the mineral 

 goldfieldite. 



