Genth.] 40 [March 18, 



Several months before this paper appeared, Mr. JoRn F. Blandj'sent me 

 from the mines near Sulphur creek, Colusa county, California, a number 

 of specimens, containing gold in minute arborescent crystals, and crystal- 

 line coatings upon quartz and chalcedony in a dark graj^ shale from the 

 mines at (h:it locality, also cinnabar and pyrite, which evidently have been 

 deposited under similar circumsiances as those mentioned by Mr [Jecker. 



The jiyrite is remarkable. It occurs in the same dark shah; as the gold 

 and appears in tabular hexagonal crystals, rarely reaching 1™™ in diame- 

 ter. A few isolated crystals arc very perfect, mostly however they are 

 grouped together or one upon the other. Their color is pale brass yellow, 

 they show very little lustre upon the basal plane, which is rather rough, 

 but bright metallic lustre upon the prismatic planes. 



A qualitative analysis showed them lobe pyrite in composition, the form 

 is that of pyrrhotite, they arc therefore pyrite, pseudomorphous after pyr- 

 rholile. 



IV. Hessite. 



An interesting variety of hessite has been found at the West Side mine. 

 Tombstone, Cochise county, Arizona, and I am indebted to Mr. Samuel 

 W. Cheyney for specimens for the same. 



It is found in vein-like strings or patches in quartz, associated with 

 cerargyrite in small crystals and crystalline coalings, a bluish green and a 

 siskingreen mineral in too small a quantity for investigation, and minute 

 grains of native gold. Color dark iron black ; spec. gr. = 8.359. 

 Soluble in nitric acid without separation of gold. 



In analysis 1, O.Gl p. c ; and in analysis 2, 3.98 p. c. of quartz were de- 

 ducted, and gave : 



1 2 



Ag = 62.87 — 62.34 



Pb = 28 — 30 



Fe = 37.34 — 37.05 



Se = trace — trace 



100.49 — 99.69 



It is remarkable that no gold is combined with the tellurium, although 

 metallic gold is associated m ith this hessite. 



V. Tapalpite. 



Prof. Carlos F. de Landero has given an account of the occurrence, the 

 properties and the composition of tapalpite from the Sierra de Tapalpa 

 (Boletin de la " Sociedad de Ingenieros" de Jalisco, Tom. v. Num. 3). 

 From an analysis of it which Prof. C. Kammelsberg had made he came to 

 the conclusion that the composition of this mineral is represented by the 

 formula : Agj S. Big Te2. 



This being exceedingly improbable, and a reexamination very desira- 

 ble, Prof. C. F. de Landero has placed me under great obligations for spe- 



