Konig.] 



476 



[June 17, 



The composition of Alaskaite is therefore in 100 parts 



Bi 



Sb 

 Pb 



Ag 

 Cu 

 Zn 



S 



56.97 

 0.62 



11.79 

 8.74 

 3.46 

 0.79 



17.63 



100.00 



This latter result must be taken as establishing the nature of Alaskaite, 

 beyond reasonable doubt. 



But on examining some other specimens qualitatively, which appeared 

 to be identical in physical characters with the preceding one, I could not 

 at first produce the crimson silver coating. Suspecting an essential difference 

 I made upon the same powder three analyses the mean of which (closely 

 agreeing) is as follows : 



0.2468 



0.1308 



0.5080 



This then is the same mineral, except that the greater 'part of the silver 

 is replaced by lead. 



"We have then in Alaskaite a complete type of the sulphosalts of the 

 first order, according to Rammelsberg's symbol : 



to wit 



(R, R) S + r^ S3 



(Pbi Zui Ag2 Cu^) S + (Bii Sb)^ S' 



Of this type several members are known, but the copper bismuth glance 

 from Schwarzenberg, and perhaps Domeyko's ore from Copiapo contain 

 bismuth exclusively on the negative side. 



The crystallographic symmetry of all the members of this type is 

 probably ortJiorJwmhic. 



A specimen from the Alaska mine, which had been sent to me as bis- 

 muth silver-ore, being composed of quartz, barite, chalcopyrite and Avhat 



