1874.] 



231 



[Genth. 



Lead 



Silver 



Bismuth 



Zinc 



Iron 



Sulphur 



The atomic ratios of Pb : Ag : Bi 

 corresponding with the composition : 

 Pb = 



Bi 



S 



100.00 

 It is allied to and closely resembles cosalite. 

 Dedicated to J. F. L. Schirmer, Esq. 



P.8. Since the reading of my paper an article has appeared in the En- 

 gineering and Mining Journal, of August 29th, 1874, on " TeUurium 

 Ores of Colorado, by Fred. M. Endlich," which I must not pass unno- 

 ticed, as it contains several statements which I cannot endorse. 



The paper shows that Dr. Endlich had not a sufficient quantity of i^ure 

 material for his examinations, and therefore based his new species upon 

 a partial examination of mixtures. 



His '^ Schirmeriie^' is evidently nothing else but a mixture of petzite, 

 either with pyrite or perhaps with a telluride of iron — a mineral which 

 has not yet been found in its pure state, the existence of which, however, 

 is probable from the fact that both the true and the auriferous hessites, 

 which are quite free from sulphur, invariably contain a minute quantity 

 of iron — which according to my analyses varies from 0.15 to 1.35 per 

 cent. 



If Dr. Endlich had given his name to a good species, I would very 

 cheerfully have adopted it and given another to my new sulphbismuthide 

 of silver and lead — but as the mixture which he describes is not entitled 

 to a name, that of " Schirmerite " must remain for my species. 



His '• Henryiie'^ is undoubtedly nothing but an altaite, with an admix- 

 ture of pyrite. 



Knowing from Mr. Schirmer, that he has given me for this investiga- 

 tion the purest and best of all the minerals which have occurred at the 

 Red Cloud Mine, I can state without hesitation that Dr. Endlich's spe- 

 cies have no existence. 



