422 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



Pyromorphite has not been definitely noted in the several surface 

 workings of the Bunker Hill mine nor in the Last Chance or Tyler 

 mines. 



In the Omaha prospect, which encountered and merged with the 

 Caledonia mine workings, long prismatic colorless pyromorphite 

 crystals (fig. 136) were found coating cracks in iron and manganese- 

 stained quartzite. In another place near the point where the 

 Sandow tunnel crosses the Caledonia line a pocket containing cup- 

 shaped olive green crystals was encountered in the roof of the tunnel. 



In the Caledonia mine large and beautifully crystalline pale-green 

 masses of pyromorphite were found in the Howard stope above the 

 300-foot level in considerable amount. Lower in the mine, as deep 

 as the 900-foot level, a peculiar pinkish pyromorphite occurs coating 

 cracks in galena or in quartzite adjacent to bodies of galena ore. 

 This pyromorphite has been previously described as follows 25 : The 

 mineral occurs commonly in crusts of minute crystals coating cracks 

 in galena or as larger crystals in cracks in quartzite. The color ranges 

 from faintly pink to colorless in the smallest crystals to quite deep 

 grayish violet in some of the largest ones. In size they range from 

 microscopic to an occasional length of 1.5 cm., the larger being those 

 in the wall rocks. Those over 5 mm. in length are commonly nearly 

 opaque with curved prism faces and .brush-like terminations. The 

 luster in the smaller crystals is adamantine, while that of the larger 

 opaque crystals is resinous. Quite commonly the crystals are at- 

 tached by a prism face and are then doubly terminated, the habit 

 being essentially like figure 134, with the length several times the 

 diameter. At times the small prisms greatly resemble quartz crys- 

 tals, the resemblance being heightened by an unequal development 

 of the pyramid faces which gives them a trigonal aspect. While 

 promising in appearance the crystals are somewhat dull and give 

 poor reflections. The forms noted were the pyramid x(10Tl) and 

 the prism m(10T0). The best crystal measured gave the value p for 

 the pyramid =40° 25', which is sufficiently close to the calculated 

 value, 40° 22' to identify the form. It is of interest to record that 

 Rush J. White, a mining engineer of Wallace, whose observations are 

 reliable, has noted the occurrence of pyromorphite in well-formed 

 crystals on the mine timbers of an abandoned drift on the 200-foot 

 level of the Caledonia mine. 26 



An unusual amount of pyromorphite was encountered in the Sena- 

 tor Stewart mine in the No. 3 tunnel, wliich is just below the grade 

 of the railroad to the Arizona tunnel of the Last Chance mine in 

 Deadwood Gulch. When the No. 3 tunnel was being driven to inter- 



25 Earl V. Shannon. Crystals of pyromorphite. Amer. Journ. Sci., vol. 43, pp. 325-327, 1917. 

 w Quoted by J. B. Umpleby. Geology and ore deposits of Shoshone County, Idaho. U. S. Oeol. 

 Survey, Bull. 732, p. 63, 1923. 



