THE MINERALS OF IDAHO 



151 



AIKINITE (138) 

 Copper lead sulphobismuthite, Cu2S.2PbS.Bi2S3. 



ADAMS COUNTY 



Orthorhombic. 



A specimen from the Seven Devils Mining district labeled 'SD 

 51, North Drift in R.R. tunnel, Seven Devils/' is a mere fragment 

 consisting largely of a white or light gray metallic mineral resembling 

 bismuthinite, intergrown with cubes of pyrite in a gangue of white 

 calcite and quartz. When the calcite was in part dissolved away by 

 acid the gray mineral was found to consist of very indistinct flattened 

 striated plates. By crushing the entire small specimen, picking out 

 the quartz and pyrite as far as possible and running the balance 

 through methylene iodide heavy solution a sample of one-fourth 

 gram was obtained for analysis. The mineral gave a strong bismuth 

 reaction with potassium iodide-sulphur mixture before the blowpipe- 

 and also gave qualitative reactions for lead and copper. The analysis, 

 recalculated to 100 per cent after deducting 7.72 per cent of quartz 

 and 5.40 per cent of pyrite gives the following percentages and 



ratios : 



Analysis and ratios of bismuth mineral from the Seven Devils 



Constituent 



Lead (Pb) . . . 

 Copper (Cu). 

 Bismuth (Bi) 

 Sulphur (S)_. 



Total.. 



Ratios 



0. 048 X 4 1. 00 X 4 



. 049 X 2 1. 02 X 2 



. 044 X 4 . 92 X 4 



.050X11 1.04X11 



These ratios give the formula Pb 4 Cu 2 Bi 4 S n or 4PbS.Cu 2 S.2Bi 2 S 3 . 

 Thus if the copper be considered cuprous it does not agree with the 

 commonly given formula for aikinite. If the copper be assumed to 

 be cupric the formula can be simplified to 3(Pb.Cu)S. Bi 2 S 3 . The 

 material was too scanty to definitely settle the exact nature of this 

 material, the single analysis made upon impure and insufficient 

 material being not dependable enough to base a new species upon 

 although it is possible that a new mineral is here represented. This 

 deserves further study upon more material. Until its nature is 

 definitely settled it may best be referred to aikinite. 



BOULANGERITE 



Lead sulphantimonite, 5PbS.2Sb 2 S3. Orthorhombic. 



Within recent years boulangerite has been found to be a rather 

 abundant constituent of ores, both in Idaho and elsewhere. Much 

 of the fibrous material which has heretofore been called jamesonite 

 is in reality boulangerite. The mineral occurs in lead-silver ores as 

 an accessory constituent, having been found abundantly both in 

 the Wood River district in Blaine Count}* and in the Coeur d'Alene 



