254 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



in leached quartz were mainly penetration and contact twins. One 

 of these furnished the measurements which are the basis for the 

 drawing, Figure 59. 



Several of the various mines of the Bunker Hill group, other 

 than the Tyler, namely the Stemwinder, Sullivan, and others, have 

 produced large amounts of carbonate ore in former years in which 

 were found cerusite crystals and crystalline masses of the types 

 already described and lease workings in these mines have obtained 

 good material in recent years. 



The Senator-Stewart mine had no very great quantities of oxidized 

 ore and in such as they had pyromorphite was perhaps more prom- 

 inent than cerusite, but some good specimens of crystallized cer- 

 usite were at times found in the upper tunnels, above the ore rail- 

 way on the high mountain west of Deadwood Gulch. 



A small mine, the Hypotheek, recently opened in French Gulch, 

 3 miles south of Kingston, has an unusually deeply oxidized ore body 

 and has produced some very fine cerusite specimens, although the 

 anglesite from this mine is still finer, as noted elsewhere. The 

 usual forms of crystallized cerusite occurred in this mine, varying 

 from colorless to pink and through various shades of gray to black. 

 This black cerusite, which was noted at this and other mines of the 

 district, was especially examined on a specimen from the Hypotheek 

 mine to determine the cause of the black color, which has been vari- 

 ously explained as due to included unoxidized galena, manganese 

 oxide, etc. The material gives a gray powder when finely ground. It 

 dissolves in hot dilute nitric acid completely and the solution does 

 not react for manganese except very faintly by the most delicate 

 permanganate test nor does it contain any sulphur. The solution of 

 the mineral in hydrochloric acid does not yield any hydrogen sulphide 

 nor does it contain any iron. The mineral is not decolorized on 

 heating nor yield any sublimate in the closed tube. These negative 

 results show that the black color is not due to manganese, iron, 

 lead sulphide, or organic matter. It seems possible that the color 

 may be due to a small amount of microscopic disseminated lead 

 dioxide, plattnerite, included in the cerusite. The most abundant 

 crystals of cerusite from the Hypotheek mine were globular masses 

 resembling a flattened cluster of grapes, pearly white in color, with 

 a silky luster. These specimens, which were found in considerable 

 numbers, embedded in soft limonite, were characteristic of the 

 mine and differed from any specimens from elsewhere in the district. 



The carbonate, in good specimens, has been reported from numer- 

 ous mines on Pine Creek and specimens have been seen from the High- 

 land Chief, Carbonate, Northern Light, and Lookout Mountain. The 

 latter property, located on the high mountain west of the forks of 

 Pine Creek, has been the most recent source for crystallized cerusite 



