NO. 2345 



CONTRIBUTIONS TO MINERALOGY— SHANNON. 



441 



In the present studies Hulyak's new forms were not observed nor 

 were il/(410) or 8(021) seen. Of the forms found, two 9 (012) and 

 iV(310), are new to the locality. 6>^(023) is a previously undescribed 

 dome which has the following angles : 



Measured. Calculated. 



c (001) A Oi (023) = 41° 32' 40° 41' 



Since it was observed only on one crystal and the observed and 

 the calculated angles do not compare very favorably this must be 

 regarded as a doubtful form. 



ANGLESITB CRYSTALS FROM THE HERCULES MINE, COEUR D'ALENE 

 DISTRICT, IDAHO. 



The Hercules mine at Burke, in the Coeur d'Alene District, pro- 

 duced from its upper levels many hundreds of tons of cerussite ore, 

 in much of which the cerussite was in fine crystals. Many beautiful 

 specimens of pyromophite and native silver and some plattnerite 

 have also been obtained from this mine, but thus far anglesite has 

 not been recorded from this or any other mine in the Canyon Creek 

 section. The writer was much interested, therefore, to find in the 

 United States National Mu- 

 seum collections a specimen 

 (Cat No. 77069-87) showing 

 well-crystallized anglesite. 



The specimen which was 

 labeled "ore, native silver,'' 

 is a mixture of earthy li- 

 monite with massive anglesite, looking precisely like the majority of 

 specimens of carbonate lead ore. Implanted upon this earthj^ mass 

 are numerous well-defined transparent anglesite crystals. Over the 

 anglesite crj-stals are strung dendritic crystalline wires of native 

 silver, now entirely blackened exteriorl}'^ by a tarnish of silver 

 sulphide. 



The anglesite crystals are tabular in development, the shape being 

 determined by the forms c{001), w(llO), and ^/(102). They roach 



Fig. 8.— Crystal of anglesite. 



Crystal of anglesite. 



an extreme length of 2 cm., although the average is about 3 milli- 

 meters, with a thickness of 1 millimeter. They fall in two types de- 

 pending on the accessory forms present. Type 1 as shown in figure 

 eight has as the dominant forms c'(OOl), 7;i(110), and d{10'2). As 

 accessory forms there are represented «(100), &(010), 2(111), 

 o(Oll), [1.(124), and p(324). Type 2 (fig. 9) has the same gen- 



