1874] 



227 



[Genth. 



seen from the analyses wliicli I give below, that there are several, from 

 almost pure hessite without gold, up to the highly auriferous of the same 

 composition as that from the Stanislaus and Golden Rule Mines in Cali- 

 fornia. 



a. Hessite. 



The pure hessite appears to be very rare. I have received only one 

 small piece, which Mr. Schirmer distinguished as "black tellurium." 

 It is of a dark iron-gray color, inclining to black, granular structure and 

 uneven fracture ; powder dark lead-gray ; sectile. Its spec. gr. = 8.178. 



It contains some cavities lined with minute crystals of pyrite and 

 barite. 



The analyses gave 

 Gold 

 Silver 

 Copper 

 Lead 

 Zinc 

 Iron 

 Tellurium 



0.33 

 59.91 



0,17 



0,45 

 trace 



1.35 

 37.86 



by diff. =n 



0.20 

 60.19 



0.16 



0,18 

 trace 



1.20 

 38.07 



99.96 100.00 



In all the other varieties, the difference in the appearance of the 

 mineral is so slight that it is almost impossible to distinguish them. 

 They all have an iron-gray color, and frequently assume by tarnishing a 

 darker or purplish color, a subconchoidal fracture ; the more argentiferous 

 are somewhat darker, the more auriferous lighter and more brittle. 



: 8.897, 



Sp. Gr. 

 Quartz 

 Gold 

 Silver 



100.97 — 100.31 



c. Petzitb. 

 a 

 9.010 

 0,63 

 24.10 

 40.73 



100,01 



/5 

 9.030 

 0.05 

 34.69 

 40,80 



