Descloizites from new Localities. 435 



of lead and zinc, which were estimated and included in the 

 analysis as probably belonging to the vanadate. The water 

 had to be estimated indirectly by deducting from the total 

 amount of water afforded by the dried mixture of vanadate 

 and gangue that beJonging to the latter alone, which was found 

 as follows. The mixture, dried at 100° C, was dissolved in 

 cold dilute nitric acid, and the insoluble matter collected in a 

 Gooch crucible was dried at the same temperature and then 

 ignited. The loss on ignition gave the water in the gangue, 

 there being no ferrous iron in the latter to influence the result. 

 The traces of Si0 2 , CaO and MgO may be neglected as proba- 

 bly derived from the gangue. The water, it will be noticed, 

 is double that required by descloizite, R 2 (OH)V0 4 , but in 

 view of the liability to error inherent in the method of water 

 estimation employed this is not deemed sufficient cause for 

 separating the mineral from descloizite, although the close 

 agreement of the two water determinations, made as they were 

 on samples containing different proportions of gangue, would 

 indicate the correctness of the formula 2[R 2 (OH)V0 4 ]-j-H 2 0. 



Other specimens have since been received from the above 

 named persons in which the earthy vanadate was associated 

 sometimes with compact cerussite and galena in process of 

 alteration. A dull reddish substance which constituted a part 

 or even the whole Of some lumps contained, besides silica, iron 

 and some antimony in an oxidized condition, but carried little 

 or no vanadium. 



Professor F. A. Genth has already called attention* to the 

 occurrence of vanadinite and probably of descloizite in the 

 Bald Mountain mine, Beaverhead County, Montana. His 

 specimens, however, showed the supposed descloizite as a pale 

 brownish crystalline coating on yellow ferruginous quartz, 

 whereas the present mineral shows no evidence of crystalline 

 structure. 



2. Commercial Mine, Georgetown, Grant County, New Mexico. 



This is one of the most interesting occurrences of descloizite 

 known, because of the extreme brilliancy of coloring of the 

 mineral. The ore bodies in the Commercial mine, as well as 

 in the adjoining MacGregor and Naiad Queen mines, occur in 

 limestone immediately under an overlying slate, and appear to 

 narrow in depth where certain eruptive dikes cut through the 

 lime, as Mr. Macintosh, foreman of the Commercial mine, in- 

 formed me. The absence of the superintendents of the several 

 mines and the very brief visit I was forced to make prevented 

 obtaining more certain and detailed information. 



* Proc. Am. Phil. Soc, xxiv, 38, 1887. 



