382 W. K. Hidden — Sperrylite in North Carolina. 



ical alteration ; the apparent great density (as shown by its 

 remaining with the gold when " panned-out " from the gravel 

 with water and also when a gentle air-blast was used in the 

 final isolation of the denser and larger particles from the 

 heavier concentrates) and its hrittleness ; all pointed to its 

 being a member of the laurite-sperrylite group, and this suppo- 

 sition was sustained by chemical tests and measurement of the 

 crystals. 



The total "find " was sent to Professor S. 1,. Penfield, who 

 very kindly reported the results of his careful examination as 

 follows (quotation from a letter dated Oct. 22, 1894) : " I 

 have tested the little crystals you sent and found distinct 

 arsenic and platinum reactions. Have measured one crystal 

 and obtained isometric angles." " My tests were as follows : 

 The crystals [55], weighing in all 0*0019 gram, were roasted in 

 an open tube and yielded a volatile sublimate of arsenious 

 oxide, crystallizing in isometric octahedrons. The residue, 

 after roasting, had the color of platinum and when dissolved in 

 nitro-hydrochloric acid gave a yellow solution, which when 

 tested with potassium chloride yielded isometric octahedrons 

 of potassium platinic-chloride." 



" The crystals showed the combination of cube and octahe- 

 dron with usually about equal development of the two forms. 

 One of the largest crystals was about 0*2 mm in diameter and 

 was measured with the following results :" 







Measured. 



Calculated 



111/slOO 



= 



54° 18' 



54° 44' 



111 zs 010 



= 



54 49 



a 



111^001 



= 



54 47 



a 



111^001 



= 



54 45 



a 



111^100 



= 



125 19 



125 16 



ni/siii 



= 



70 25 



70 32 



" The foregoing angles indicate that the crystals are iso- 

 metric like the sperrylite from the Algoma district, near Sud- 

 bury, Canada." 



No sperrylite or gold has as yet been found in situ or in 

 bowlders in the Cowee district, but the abundance of horn- 

 blendic-gneiss and the constant occurrences in it of seams and 

 disseminated pyrite, chalcopyrite, nickeliferous-pyrrhotite and 

 sphalerite, indicate that sperrylite can now be searched for, 

 with confidence, all along the pyritous belt of western North 

 Carolina, or in similar Sudbury-like situations. 



Pyrite found in cavities in situ, one-half a mile east (up- 

 creek) of the "Ned Wilson Branch," had the exact habit of 

 the sperrylite crystals found in the gravel below. 



