THE MINERALS OF IDAHO 



447 



site crystals. Over the anglesite crystals are strung dendritic crystal- 

 line wires of native silver, now entirely blackened exteriorly by a 

 tarnish of silver sulphide. 



The crystals are tabular in development the shape being deter- 

 mined by the forms c(001), m(110), and eZ(102). They reach an 

 extreme length of 2 cm., although the average is about 3 mm., with 

 a thickness of 1 mm. The habit is illustrated in the drawings, 

 Figures 146 and 147. As accessory forms there are small faces of 

 a(100), 6(010), 2(111), o(011), (124) p(324), n(120), t(l2l), 1(104), 

 and one new form, a dome, lettered Fi which gives the indices (1- 

 0-14). This- was observed only once as a line face yielding a poor 

 signal. It gave the following angles: 



Angles oj new form F\ (1-0-14) 



Figs. 150-151.— Anglesite. Hypotheek mine, Shoshone County 



In the Last Chance mine prismatic flattened crystals, elongated 

 on the h axis were occasionally found in cavities in galena, although 

 in many specimens there was no anglesite but instead clear cerusite 

 crystals resting on the unaltered galena. Some of the anglesite 

 crystals reached an extreme length of 5 cm., their habit being similar 

 to Figure 153. These were commonly smoky gray to black from 

 included unoxidized galena. 



In the adjacent Tyler mine anglesite was frequently found in 

 cavities in galena and associated with decomposing pyrite. Most 

 of the crystals from this mine were extremely simple many of them 

 simply consisting of the unit prism m(110) and the base c(001), 

 although small faces of the domes o(011) and d(\02) usually occurred. 

 Often vertically elongated crystals showed notched edges due to 

 parallel growth (o). A crystal from this locality, now in the Brush 

 collection, of rhombohedral aspect showing m and c with minute 



