W. F. Hillebrand — Vanadium Sulphide, Patronile. 151 



"When the powder was exposed over night in a covered plati- 

 num crucible to the action of strong hydrofluoric acid, nearly 

 half the vanadium and much of the silica, alumina and titanium 

 w r ere extracted, but only about one twenty-fifth of the iron and 

 nickel, these two showing exactly the ratio afforded by the 

 main analysis below. Boiling with dilute sulphuric acid yielded 

 results somewhat similar. 



If the vanadium is disregarded, the iron-nickel sulphide has 

 the formula (FelSri)S 2 with iron to nickel as 1*70 to 1, or nearly 

 5 to 3. A pyrite with such a high proportion of nickel is 

 unknown. But a single one of the analyses quoted in Hintze's 

 Handbook of Mineralogy shows anywhere near 6 per cent 

 nickel, this one, however, showing also about 3 per cent of 

 cobalt. The nearest approach to the present case is seen in the 

 mineral gunnarite 3FeS 2 ,2MS, incompletely described by Lancl- 

 strom (Geol. Foren., ix, 368, 1887,) with density 4*3 and a tin- 

 white color with a tinge of yellow, tarnishing yellowish brown. 

 The present mineral would seem to be quite distinct from 

 gunnarite and for the present is to be regarded as a highly 

 nickeliferous pyrite. Should it seem proper to give it a specific 

 name later, bravoite is suggested, after Senor Jose J. Bravo, 

 the Peruvian writer on the vanadium occurrence at Minasragra. 



The Carbonaceous Material of the Ore. 



A determination of carbon and sulphur in 0*2459 gram of 

 the residue insoluble in alkali and nitric acid gave 0*0475 

 carbon and 0-0254 sulphur, of which last 0*0036 was soluble in 

 carbon disulphide. These figures indicate a similarity to quis- 

 queite, although the sulphur is lower. 



The Oxidation Products of the Ore. 



Oxidation products are reported to cover the surface of the 

 ground in the vicinity of the vein outcrop. The specimen 

 examined by me resembles porous limonite in appearance. 

 There was found in it by a rough partial analysis about 

 45 per cent Y 2 5 , 14-15Fe 2 3 , 15H 2 0, 20 or more of siliceous 

 gangue, nearly 1 of Mo0 3 and a little S0 3 . Nickel is absent, 

 or practically so. The material does not represent a single 

 species, for it contains probably more than one vanadium com- 

 pound, among them doubtless the minute micaceous scales, 

 greenish sometimes and sometimes yellowish, that may be seen 

 with a lens. 



Lab. IT. S. Geological Survey, 

 May 22, 1907. 



